简介：Heattransportisakeyenergeticprocessinmaterialsanddevices.Thereducedsamplesize,lowdimensionoftheproblemandtherichspectrumofmaterialimperfectionsintroducefruitfulphenomenaatnanoscale.Inthisreview,wesummarizerecentprogressesintheunderstandingofheattransportprocessinlow-dimensionalmaterials,withfocusontherolesofdefects,disorder,interfaces,andthequantummechanicaleffect.Newphysicsuncoveredfromcomputationalsimulations,experimentalstudies,andpredictablemodelswillbereviewed,followedbyaperspectiveonopenchallenges.

简介：Thispapergivesanoverviewonnonlinearporousflowinlowpermeabilityporousmedia,revealsthemicroscopicmechanismsofflows,andclarifiespropertiesofporousflowfluids.Itshowsthat,deviatingfromDarcy’slinearlaw,theporousflowcharacteristicsobeyanonlinearlawinalow-permeabilityporousmedium,andtheviscosityoftheporousflowfluidandthepermeabilityvaluesofwaterandoilarenotconstants.Basedonthesecharacters,anewporousflowmodel,whichcanbetterdescribelowpermeabilityreservoir,isestablished.Thismodelcandescribevariouspatternsofporousflow,asDarcy’slinearlawdoes.Alltheparametersinvolvedinthemodel,havingdefinitephysicalmeanings,canbeobtaineddirectlyfromtheexperiments.

简介：TheaerodynamicforcesandflowstructureofamodelinsectwingisstudiedbysolvingtheNavier-Stokesequationsnumerically.Afteraninitialstartfromrest,thewingismadetoexecuteanazimuthalrotation(sweeping)atalargeangleofattackandconstantangularvelocity.TheReynoldsnumber(Re)consideredinthepresentnoteis480(Reisbasedonthemeanchordlengthofthewingandthespeedat60%winglengthfromthewingroot).Duringtheconstant-speedsweepingmotion,thestallisabsentandlargeandapproximatelyconstantliftanddragcoefficientscanbemaintained.Themechanismfortheabsenceofthestallorthemaintenanceoflargeaerodynamicforcecoefficientsisasfollows.Soonaftertheinitialstart,avortexring,whichconsistsoftheleading-edgevortex(LEV),thestartingvortex,andthetwowing-tipvortices,isformedinthewakeofthewing.Duringthesubsequentmotionofthewing,abase-to-tipspanwiseflowconvertsthevorticityintheLEVtothewingtipandtheLEVkeepsanapproximatelyconstantstrength.ThispreventstheLEVfromshedding.Asaresult,thesizeofthevortexringincreasesapproximatelylinearlywithtime,resultinginanapproximatelyconstanttimerateofthefirstmomentofvorticity,orapproximatelyconstantliftanddragcoefficients.Thevariationoftherelativevelocityalongthewingspancausesapressuregradientalongthewingspan.Thebase-to-tipspanwiseflowismainlymaintainedbythepressure-gradientforce.

简介：高度强制的钴铁酸盐nanoparticles被他们的暂停的直接注射为加热为磁性的过高热综合并且学习进一个强壮的听觉频率的磁场的一个肿瘤和应用。物理(在液体和稳固的分散的动态磁性的磁滞现象和热产生)，生物(在进老鼠肿瘤织物的治疗学的数量的粒子的毒性和穿入)象其它一样，粒子的性质被学习。一个模型被开发为Brownian和常规旋转与一篇报道在磁性的nanoclusters的暂停描述magnetodynamics，到提供观察现象的理解。开发的试验性、理论的技术为低频率的热产生为磁性的nanoparticles的可控制的合成形成了一个基础在医药并且另外的应用程序。

简介：Coherentstructuresareessentialforthemomentumexchangeandturbulenceproductioninwall-boundedturbulentflows.Diversifiedcoherentstructureshavebeenobservedinturbulentboundarylayers,andhairpin-basedvorticesdominatemostoftherelevantliterature.However,thereisnoconsensusyetontheoriginandformingmechanismofhairpinvortices.Herein,fivecornerstonespertainingtotheframeworkofhairpin-basedcoherentstructuresarereviewed,andthreedifferenthairpingenerationmechanismsareclarified.Next,thetime-resolvedtomographicparticleimagevelocimetry(Tomo-PIV)isusedinanearlyturbulentboundarylayer(Reθ=420)toinvestigatetheoriginofhairpinvortices.Thetimelinesrevealatriangularbulgeinthelow-speedstreak(LSS),andtheinitialroll-upoccursattwosidesofit.Meanwhile,thematerialsurfacesmanifestasathree-dimensional(3D)wavestructureintheLSS,whichmaysupportthemodelofasoliton-likecoherentstructure(SCS).Subsequently,themethodofLagrangian-averagedvorticitydeviationisusedtodetectearlyvortices.Wefindthatthe3Dwavestructureisflankedbytwovortices,thusconfirmingtheroll-upoftimelinesanddemonstratingtheadvantageoftheLagrangiancriteriaincapturingstructuresincomplexflows.Theseresultssuggestthatvariouscoherentstructuresmayevolvefromthemetamorphosisof3Dwavestructuresandtheirlaterinteraction.Finally,thelimitationsoftraditionalexperimentalandpost-processingtoolsarediscussed.

简介：Thepolarlowandtropicalcyclonetypevorticesovertopographyareassumedtobetheaxisymmetricalandthermal-windbalancedsystems,whicharesolvedasaninitialvalueproblemofalinearizedvortexequationsetincylindricalcoordinates.Therolesofthesensibleandlatentheating,friction,andtopographyinthestructureandintensificationofthepolarlowandtropicalcyclonetypevorticesareanalyzed.Theradialvelocity,verticalvelocity,azimuthalvelocity,andtheunstablegrowthrateincludingthetopographyeffectsareobtained.Itisshownthattheinteractionbetweentheflowandthetopographyplaysasignificantroleinthestructureandintensificationofthepolarlowandtropicalcyclonesystem.Theanalysisofthetopographytermindicatesthat,intheup-slopesideofthemountain,theradialinflowandtheverticalascentforcedbythemountaincanintensifythepolarlowandtropicalcyclonetypevortexandincreasetheunstablegrowthrate.However,intheleesideofthemountain,theradialinflowandtheverticaldescentforcedbythemountaincanweakenthepolarlowandtropicalcyclonetypevortexanddecreasetheunstablegrowthrateofthepolarlowandtropicalcyclonesystem.Inaddition,theevolutionaryprocessandthespatialstructureofthepolarlowobservedovertheJapanSeaon19December2003areinvestigatedwiththeobservationaldatatoverifythistheoreticalresult.

简介：Spacecraftsciencemissionstoplanetsorasteroidshavehistoricallyvisitedonlyoneorseveralcelestialbodiespermission.Theresearchgoalofthispaperistocreateatrajectorydesignalgorithmthatgeneratestrajectoryallowingaspacecrafttovisitasignificantnumberofasteroidsduringasinglemission.Fortheproblemofglobaltrajectoryoptimization,evenwithrecentadvancesinlow-thrusttrajectoryoptimization,afullenumerationofthisproblemisnotpossible.Thisworkpresentsanalgorith...

简介：

简介：

简介：Alow-diffusionpreconditioningRoeschemewithanadjustableparametertocontrolthenumericaldissipationisproposed.Thisschemereflectstherealphysicaldissipationintheextremelylow-speedregion.Thepreconditioningparameterinschemeisimprovedbylinearcut-offandcorrectionfactor.Thenumericalresultsoflow-Mach-number/low-Reynolds-numbersteadysolutionsofviscousflowspastacircularcylinderandpastaNACA0012airfoilshowtheefficiencyofthenewscheme.

简介：首先，有不同坚硬的粒子的低速度的传送的特征试验性地以流动模式和压力落下在一条水平管道被调查证明蛞蝓流动能被分类进取决于沿着管道安定粒子的二种类型，并且没有解决的层，时期为蛞蝓流动是小的，它被叫独居的蛞蝓流动。为软粒子的压力落下被显示为难粒子比那大。然后，试验性的结果在证明从传送隧道的最高的表面的那个空气版本是为粒子的高集体的流动率的一个重要因素的好粉末的水平使流体化床的传送上被介绍。

简介：Theconstitutiveequationunderthelow-cyclefatigue(LCF)wasdiscussed,andatwo-dimensional(2-D)modelforsimulatingfatiguecrackextensionwasputforwardinordertoproposeanewcyclicJ-integral.Thedefinition,primarycharacteristics,physicalinterpretationsandnumericalevaluationofthenewparameterwereinvestigatedindetail.Moreover,thenewcyclicJ-integralforLCFbehaviorswasvalidatedbythecompacttension(CT)specimens.ResultsshowthatthecalculatedvaluesofthenewparametercancorrelatewellwithLCFcrackgrowthrate,duringconstant-amplitudeloading.Inaddition,thephenomenonoffatigueretardationwasexplainedthroughtheviewpointofenergybasedontheconceptofthenewparameter.

简介：在骨头的Microdamage累积在破裂过程期间是为精力驱散的机制之一。在骨头成分的超微结构和作文的变化能由于老化或疾病影响microdamage累积。钠氟化物(NaF)的低集中(1mM)在这研究被使用了在跟随免费秋天的影响装载的老鼠胫骨在microdamage累积上调查ultrastructural变化的效果。22根胫骨随机被划分成控制和对待NaF的组。装载的免费秋天的影响在每根胫骨上被进行两次生产microdamage。对待NaF的胫骨的有弹性的模量在影响装载以后显著地减少了，当在未经治疗的样品在之间的模量没有重要差别时预先损坏并且损坏以后的装载。Microdamage形态学分析少些显示出那，更短的microcracks与控制骨头相比在对待NaF的胫骨存在。同时，更多和更长的microcracks在压缩区域与那相比在未经治疗的样品在张力的区域被观察，而没有重要差别在对待NaF的骨头在张力、压缩的区域之间被观察。这研究的结果显示更多的精力被要求比在正常骨头在对待NaF的骨头产生microcracks。氟化物处理的低集中可以在装载的影响下面增加骨头的坚韧。这研究在ultrastructural的效果上集中了的图形的摘要在影响装载下面在骨头在microdamage上变化。对待NaF的胫骨的有弹性的模量在影响装载以后显著地减少了。更少和更短的microcracks在对待NaF的胫骨骨头存在。更多的精力被要求在对待NaF的骨头产生microdamage。氟化物处理的低集中可以增加骨头的坚韧。

简介：Carbon-manganesesteelisoftenappliedincomponentsofpipesinnuclearplant.Ultrasonicfatiguetestsfollowinglowcyclefatigue(LCF)cyclesdamagedareusedtostudythestrengthofveryhighcyclefatigure(VHCF).ThecomparisonoftestresultsofsimpleVHCFandcumulativefatigue(LCFplusVHCF)showsthatLCFloadinfluencesthefollowingVHCFstrength.ContinuumdamagemechanicsmodelisextendedtoVHCFregion.TheeffectofLCFloadonVHCFisstudiedbyanimprovedcumulativedamagemodel.

简介：

简介：Wepresentadesignmethodforcalculatingandoptimizingsoundabsorptioncoefficientofmulti-layeredporousfibrousmetals(PFM)inthelowfrequencyrange.PFMissimplifiedasanequivalentidealizedsheetwithallmetallicfibersalignedinonedirectionanddistributedinperiodichexagonalpatterns.Weuseaphenomenologicalmodelintheliteraturetoinvestigatetheeffectsofporegeometricalparameters(fiberdiameterandgap)onsoundabsorptionperformance.ThesoundabsorptioncoefficientofmultilayeredPFMsiscalculatedusingimpedancetranslationtheorem.Todemonstratethevalidityofthepresentmodel,wecomparethepredictedresultswiththeexperimentaldata.Withtheaveragesoundabsorption(lowfrequencyrange)astheobjectivefunctionandthefibergapsasthedesignvariables,anoptimizationmethodformulti-layeredfibrousmetalsisproposed.Anewfibrouslayoutwithgivenporosityofmulti-layeredfibrousmetalsissuggestedtoachieveoptimallowfrequencysoundabsorption.Thesoundabsorptioncoefficientoftheoptimalmulti-layeredfibrousmetalishigherthanthesinglelayeredfibrousmetal,andasignificanteffectofthefibrousmaterialonsoundabsorptionisfoundduetothesurfaceporosityofthemulti-layeredfibrous.

简介：在与喉咙直径的一张超声的嘴相结合的一个低动力的弧气体加热器的流动不到1mm相当复杂、困难在量的详细描述。单原子的气体氩和氦的加热弧的超声的喷气推进器的实验被执行了，他们的表演测量了。流动特征在数字模拟的帮助下被分析。结果证明粘滞效果是引起理想、真实的性能之间的大差别的最重要的因素。出口流动的大外部节是慢吞吞的。这在氦是特别显著的，在嘴的70%出口区域可能在亚声的流动的地方。磨擦力量能比网推进的大得多，在氦更高若干次到达，导致很低的效率。引起理想、真实的流动之间的差别的另外的因素包括：在喉咙区域，延长到嘴扩大节的电的弧，到入口气体并且从热血浆的热转移，和在真空房间的环境压力的复杂流动。当处理如此的复杂状况时，超声的嘴流动的平常的概念必须极大地被修改，这被认出当处理如此的复杂状况时。在这份报纸介绍的一般概念能在指导这台设备的设计和操作是有用的。

简介：Purenitrogengaswasheatedwithdirectcurrentarc,atinputpowersfromseveralhundredWtoover5kW,andtheninjectedthroughanozzleintoachamberat1or10Papressure,withthepurposeofacceleratingthegastoveryhighspeedaround7km/s.Variousstructuresofthearcgeneratorandgasexpansionnozzlewereexamined.Resultsshowthatbypassexhaustingoftheboundarylayerbeforeitentersthenozzledivergentsectioncangreatlyincreaseflowspeedofthejet,thusitmightbepossibletousenitrogenasaworkinggasinhighspeedgasdynamictestfacilities.att

简介：

简介：Inthisstudy,one-dimensionaltitaniananotubes(TNTs)weresynthesizedusingacombinedprocessofchemicalandhydrothermaltreatments,andtheiractivitiesforthephotocatalyticreactionsofselectedgaseouspollutantsatsub-ppmlevelsweredetermined.Additionally,thepropertiesoftheTNTswereexaminedusingselectedspectroscopicmethods.TheannealedTNTsshowedhigherphotocatalyticactivitiesforthefourtargetcompoundsthandidtheunannealedTNTs.Forallthetargetcompoundsexceptbenzene,theeffectoftheannealingtemperatureonthedegradationefficiencywasdifficulttodeterminebecausealldegradationefficiencieswereveryhigh.However,forbenzene,whichdecomposedwithalowefficiency,thedegradationactivitiesoftheTNTsincreasedasthetreatmenttemperaturewasincreasedfrom250to300℃,whiletheydecreasedslightlywhenthetemperaturewasincreasedfrom300to400℃.ThesefindingsconfirmthepresenceofanoptimalannealingtemperatureforthesynthesisofTNTs.Moreover,theaveragedegradationextentsforbenzene,toluene,ethylbenzene,ando-xylenedecreasedfrom92%,96%,99%,and98%to77%,86%,92%,and94%,respectively,astheairstreamflowrateincreasedwithintherangeof1-4L/min.Theaveragedegradationextentsdecreasedfrom12%,75%,87%,and88%to3%,29%,46%,and51%,respectively,astheinputconcentrationincreasedfrom0.4to1.9ppm.Overall,thesefindingssuggestthatone-dimensionalTNTscanbeeffectivelyutilizedforthedegradationofgaseouspollutantsunderoptimaloperationalconditions.