简介：Veryhighcyclefatigue(VHCF)behaviorsofbridgesteel(Q345)weldedjointswereinvestigatedusinganultrasonicfatiguetestsystematroomtemperaturewithastressratioR=-1.Theresultsshowthatthefatiguestrengthofweldedjointsisdroppedbyanaverageof60%comparingtothebasemetalandthefatiguefailurestilloccurredbeyond10~7cycles.Thefatiguefractureofweldedjointsinthelowcycleregimegenerallyoccurredatthesolderwhileattheheat-affectedzone(HAZ)intheveryhighcycleregime.Thefatiguefracturesurfacewasanalyzedwithscanningelectronmicroscopy(SEM),showingweldingdefectssuchaspore,micro-crackandinclusionwerethemainfactorsondecreasingthefatiguepropertiesofweldedjoints.Theeffectofweldingdefectsonthefatiguebehaviorsofweldedjointswasdiscussedintermsofexperimentalresultsandfiniteelementsimulations.

简介：Basedonthetheoryofcouplingvibrationandflexuralvibrationofthinrodofrectangularcrosssection,thefiexuralvibrationofrectangularthinplatewasstudied.Thefrequencyequationwasderivedundertheconditionoffreeboundaries.Thenormalmodesandtherelationbetweenthenormalmodesandtheresonantfrequencywereobtained.Experimentsshowedthatthecalculatedresonantfrequenciesagreewellwiththemeasuredresults,andtherectangularthinplateinflexuralvibrationhasabundantresonantfrequencies.Theradiatorofflexuralvibrationusedinultrasoniccleaningandothertechniqueshastheadvantagesoflargeacousticradiatingarea,uniformacousticfieldandeasyadjustmentofresonantfrequencies,provingthatitisapromisingultrasonicsource.

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简介：Anewoxidationkineticsmodelisestablishedforhigh-temperatureoxidation.Weassumethattheinterfacereactionisfastenoughandtheoxidationrateiscontrolledbydiffusionprocessathightemperature.Byintroducingthegrowthstressgradientwemodifytheclassicaloxidationparaboliclaw.Themodifiedfactoroftheoxidationrateconstantisafunctionofgrowthstrain,environmentoxygenconcentration,andtemperature.Themodelingresultsshowthatthestressgradienteffectontheoxidationratecannotbeignored.Growthstrainwilldominatewhetherthestressgradienteffectpromotesorslowsdowntheoxidationprocess.Thestressgradienteffectbecomesweakerathighertemperature.Thiseffectisamplifiedathigherconcentrationsofenvironmentaloxygen.Appliedmechanicalloadsdonotaffecttheoxidationrate.Thismodelisavailableforhightemperatureoxidationofmetalsandalloys.

简介：Thispapernumericallystudiestheinfluenceofthedownwardspoilerdeflectionontheboundarylayerflowofahigh-lifttwo-elementairfoilconsistingofadroopnose,amainwing,adownwarddeflectingspoilerandasingleslottedflap.Bothoftheboundarylayeroftheuppersurfaceofthespoilerandtheconfluentboundarylayeroftheuppersurfaceoftheflapbecomethicker,asthedownwardspoilerdeflectionincreases.Comparedtotheattachedflowattheangleofattackof10°,theflowoftheuppersurfaceofthespoilerbecomesseparatedattheangleofattackof16°whenthespoilerdeflectionislargeenough,whichcorrespondstotheboundarylayerflowreversalinvelocityprofiles.

简介：新奇的肼单体，pyridine-2，6二度((4-aminophenyl)thioureido)羰基(PATC)高效地被综合并且有各种各样的芳香的dianhydrides的polymerized。因而，(pyridinethiourea-imide)poly，有好热性质的s(PPTI)和火焰retardancy被制作。PATC和PPTI的结构被FTIR描绘，<啜class=“a-plus-plus”>1H-NMR，<啜class=“a-plus-plus”>13与元素的分析，crystallinity，organosolubility，固有的粘性和胶化浸透一起的C-NMR光谱学色析法的大小。包含C=S，CONH和元的PPTI在聚合物脊梁代替了pyridine一半显示出非结晶的自然并且在高度极的器官的溶剂并且甚至在象tetrahydrofuran(THF)那样的不太极的溶剂是容易地可溶的。聚合物在0.911.16dL/g的范围有固有的粘性，分子的重量在6800077000g/mol之间被发现。PPTI的电的性质以在频率的一个范围上经常的电介质被估计。他们的热稳定性被在范围发现的10%重量损失温度决定519563在组之中未改变。1/1-sGC子单元的蛋白质层次从中年的比较w相?盼?盼在RCC被减少吗？？

简介：In2018,thejournalHighPowerLaserScienceandEngineeringproducedaSpecialIssueonFibresforHighPowerLasers.Nowadays,fibre-basedlasersourceshavefoundextensiveapplicationsbothinindustryandinscientificresearch.Thescopeofthespecialissuewastospanthelatestdevelopmentsonthefastdevelopingfibre-basedhigh-powerlasersandamplifiers.Thetopicsinvitedforinclusionwere:

简介：Forapreviouslysimulatedeight-broadbandnegative-refraction-indexchiralmetamaterial,weuseS-parameterretrievalmethodstodeterminethecomplexeffectivepermittivity,permeability,andtheimpedance.Wealsocalculatethefigureofmerit,whichisdefinedastheratiooftherealandtheimaginaryrefractioncomponents,andcompareitwiththoseoffishnetmetamaterials.Thesimulationresultsshowthatourchiralmetamaterialexhibitshightransmissionandimpedancematchingtoavacuum.Also,wedeterminethattheelectricandmagneticdipolesofthesurfaceplasmonsplayanimportantroleindeterminingthenineresonancefrequencies.Therefore,thisinvestigationprovidesanexperimentalbasisfordevelopingmetamaterialdeviceswithmultipleandbroadresonancefrequencybands.

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简介：Recentlytherehasbeengreatprogressinlaser-drivenplasma-basedacceleratorsbyexploitinghigh-powerlasers,whereelectronbeamscanbeacceleratedtomulti-GeVenergyinacentimeter-scaleplasmaduetothelaserwakefieldaccelerationmechanism.While,todate,worldwideresearchonlaserplasmaacceleratorshasbeenfocusedonthecreationofcompactparticleandradiationsourcesforbasicsciences,medicalandindustrialapplications,thereisgreatinterestinapplicationsforhigh-energyphysicsandastrophysics,exploringunprecedentedhigh-energyfrontierphenomena.Inthiscontext,wepresentanoverviewofexperimentalachievementsinlaserplasmaaccelerationfromtheperspectiveoftheproductionofGeV-levelelectronbeams,anddeducethescalingformulascapableofpredictingexperimentalresultsself-consistently,takingintoaccountthepropagationofarelativisticlaserpulsethroughplasmaandtheacceleratingfieldreductionduetobeamloading.Finally,wepresentdesignexamplesfor10-GeV-levellaserplasmaacceleration,whichisexpectedinnear-termexperimentsbymeansofpetawatt-classlasers.

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简介：Physicsexperimentsthatgeneratelargeamountsofdataneedtobeabletoshareitwithresearchersaroundtheworld.Highperformancegridsfacilitatethedistributionofsuchdatatogeographicallyremoteplaces.Dynamicreplicationcanbeusedasatechniquetoreducebandwidthconsumptionandaccesslatencyinaccessuingthesehugeamountsofdata.Wedescribeasimulationframeworkthatwehavedevelopedtomodelagridscenario,whichenablescomparativestudiesofalternativedynamicreplicationstrategies.Wepresentpreliminaryresultsobtainedwiththissimulator,inwhichweevaluatetheperformanceofsixdifferentreplicationstrategiesforthreedifferentkindsofaccesspatterns.Thesimulationresultsshowthatthebeststrategyhassignificantsavingsinlatencyandbandwidthconsumptioniftheaccesspatternscontainamoderateamountofgerographicallocality.

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简介：Developinganelectrostaticdischarge(ESD)protectiondevicewithabetterlatch-upimmunityhasbeenachallengingissueforthenanometercomplementarymetal-oxidesemiconductor(CMOS)technology.Inthiswork,animprovedgrounded-gateN-channelmetal-oxidesemiconductor(GGNMOS)transistortriggeredsilicon-controlledrectifier(SCR)structure,namedGGSCR,isproposedforhighholdingvoltageESDprotectionapplications.TheGGSCRdemonstratesadoublesnapbackbehaviorasaresultofprogressivetrigger-onoftheGGNMOSandSCR.Thedoublesnapbackmakestheholdingvoltageincreasefrom3.43Vto6.25Vascomparedwiththeconventionallow-voltageSCR.TheTCADsimulationsarecarriedouttoverifythemodesofoperationofthedevice.

简介：ThispapercarriesouttheFirstprinciplescalculationofthecrystalstructures(zincblende(B3)androcksalt(B1))andphasetransitionofboronarsenic(BAs)basedonthedensity-functionaltheory.Usingtherelationbetweenenthalpyandpressure,itfindsthatthetransitionphasefromtheB3structuraltotheB1structuraloccursatthepressureof113.42GPa.ThentheelasticconstantsC11,C12,C44,bulkmodulus,shearmodulus,Youngmodulus,anisotropyfactor,KleinmanparameterandPoissonratioarediscussedindetailfortwopolymorphsofBAs.TheresultsofthestructuralparametersandelasticpropertiesinB3structureareingoodagreementwiththeavailabletheoreticalandexperimentalvalues.

简介：Thispaperpresentsacomputationalmodelforthefluiddynamicsinafracturedductilepipeunderhighpressure.Thepressureprofileinfrontofthecracktip,whichisthedrivingsourceofcrackpropagation,iscomputedusinganonlinearwaveequation.Thesolutioniscoupledwithaonedimensionalchokedflowanalysisbehindthecrack.Thesimulationutilizesahighorderoptimizedprefactoredcompact-finitevolumemethodinspace,andlowdispersionanddissipationRunge-Kuttaintime.Asthepipefracturestherapiddepressurizationtakeplaceinsidethepipeandthepropagationofthecrack-inducedwavesstronglyinfluencestheoutflowdynamics.Consistentwiththeexperimentalobservation,themodelpredictstheexpansionwaveinsidethepipe,andthereflectionandoutflowofthewave.Themodelalsohelpscharacterizethepropagationofthecrackdynamicsandfluidflowsaroundthetipofthecrack.

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简介：Adetailedstudywasperformedonthecrystalstructuresofpan-milledhigh-densitypolyethylene(HDPE)usingdifferentialscanningcalorimetry(DSC)andX-raydiffraction.ThecrystallinityofHDPEfirstdecreasedslightly,followedbyagradualincreasewithincreasingmillingtimes.Monocliniccrystalsappearedafter4cyclesofmilling.Withincreasingtimesofmilling,theproportionofmonocliniccrystalsincreasedsignificantlywhiletheproportionoforthorhombiccrystalsdecreasedgradually.Withincreasingtimesofmilling,thecrystallitesizeoforthorhombicformdecreasedgreatly,whilethesizeofmonocliniccrystalliteskeptalmostconstantduringmilling.

简介：利用天然气脱硫厂的酸气、氢氧化钠、对二氯苯和助剂磷酸钠，在六甲基苯磷酰三胺溶剂中，常压下缩聚４～６小时，制备了线型结晶性高分子量聚苯硫醚（ＨＭＷＰＰＳ）。该方法具有的明显优点是：设备简单、容易操作、活性高、溶剂稳定、产品收率高、成本低、适宜于大规模工业生产。