简介：Someofthemostinterestingrefractionpropertiesofphononiccrystalsarerevealedbyexaminingtheanti-planeshearwavesindoublyperiodicelasticcompositeswithunitcellscontainingrectangularand/orellipticalmultiinclusions.Thecorrespondingbandstructure,groupvelocity,andenergy–fluvectorarecalculatedusingapowerfulmixedvariationalmethodthataccuratelyandefficientlyieldsallthefielquantitiesovermultiplefrequencypass-bands.Thebackgroundmatrixandtheinclusionscanbeanisotropic,eachhavingdistinctelasticmoduliandmassdensities.Equifrequencycontoursandenergy–fluvectorsarereadilycalculatedasfunctionsofthewave-vectorcomponents.Bysuperimposingtheenergy–fluvectorsonequifrequencycontoursintheplaneofthewave-vectorcomponents,andsupplementingthiswithathree-dimensionalgraphofthecorrespondingfrequencysurface,awealthofinformationisextractedessentiallyataglance.Thiswayitisshownthatacompositewithevenasimplesquareunitcellcontainingacentralcircularinclusioncandisplaynegativeorpositiveenergyandphasevelocityrefractions,orsimplyperformsaharmonicvibration(standingwave),dependingonthefrequencyandthewave-vector.Moreover,thatthesamecompositewheninterfacedwithasuitablehomogeneoussolidcandisplay:(1)negativerefractionwithnegativephasevelocityrefraction;(2)negativerefractionwithpositivephasevelocityrefraction;(3)positiverefractionwithnegativephasevelocityrefraction;(4)positiverefractionwithpositivephasevelocityrefraction;oreven(5)completereflectiowithnoenergytransmission,dependingonthefrequency,anddirectionandthewavelengthoftheplane-wavethatisincidentfromthehomogeneoussolidtotheinterface.Forellipticalandrectangularinclusiongeometries,analyticalexpressionsaregivenforthekeycalculationquantities.Expressionsfordisplacement,velocity,linearmomentum,strain,andstresscomponents,aswellastheenergy–fluandgroupveloc

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简介：Thepile-soilsystemisregardedasavisco-elastichalf-spaceembeddedpile.Basedonthemethodofcontinuummechanics,anonlinearmathematicalmodelofpilesoilinteractionwasestablished-acouplingnonlinearboundaryvalueproblem.Underthecaseofhorizontalvibration,thenonlinearlydynamicalcharacteristicsofpileapplyingtheaxisforcewerestudiedinhorizontaldirectioninfrequencydomain.Theeffectsofparameters,especiallytheaxisforceonthestiffnesswerestudiedindetail.Thenumericalresultssuggestthatitispossiblethatthepileapplyinganaxisforcewillloseitsstability.So,theeffectoftheaxisforceonthepileisconsidered.

简介：Theobjectivesofthisresearchweretocharacterisetheclaymineralscompositionofsoil-deriveddustinNorthernChinaandtosetupamineralogicalsignaturetotracetheirorigin.MineralcompositionofaerosolparticleswasinvestigatedatAksu,Dunhuang,Yulin,TongliaoandChangwuduringanintensivefieldcampaignperiodofACE-Asia.Theresultsshowthatthekaolinite(K)tochlorite(C)ratioissensitivetotheregionaloriginofAsiandust.Westernsourceareas(representedbyAksu)displayedthelowestK/Cratioof0.3(average),whileitwasfoundtoincreaseupto0.70(average)uponmovingtowardsnorthernsourceareas(representedbyYulin).BystudyingtransporteddustinadepositionarearepresentativeoftheChineseLoessPlateau,theusefulnessoftheK/Cratio,whenassociatedwithbackair-masstrajectories,wasfoundtolieinrevealingtheoriginofthedust.ComparisonofthemineralogicaldatabetweenAsiandustandSaharadust,showsthattheK/Cratioisalsoaneffectivesignaturetoidentifythesourceareasonahemispherescale.

简介：Measurementsofparticulatematter(PM),i.e.,PM10,PM2.5,andPMl,havebeenperformedontheCantonTower,alandmarkbuildinginGuangzhou,atheightsof121and454msinceNovember2010,usingaGRIMM180aerosolparticlespectrometer(Germany).AnalysesofdatafromNovember2010toMay2013showedthattheannualaveragevaluesofPM10,PM2.5,andPMlattheobservationheightof121mabovethegroundwere44.1,38.2,and34.9μg/m3,respectively,andthoseat454mabovethegroundwere35.7,30.4,and27.5μg/m3,respectively.ByconsideringthevaluesofthesecondaryconcentrationlimitsgivenintheAmbientAirQualityStandardsissuedin2012,itwasobservedthattheannualaveragevaluesofPM10attheobservationheightsof121and454m,aswellasthoseofPM2.5at454m,reachedthosestandards.Furthermore,theover-standardamplitudeoftheannualaveragevalueofPM2.5attheobservationheightof121mwas9.1%.Duringtheobservationperiod,themaximumdailyaveragevaluesofPM10,PM2.5,andPM1attheobservationheightof121mwere183.3,144.8,and123.8μg/m~3,respectively,andthoseat454mwere102.8,92.7,and86.4μg/m3.ThedailyaveragevaluesofPM10attheobservationheightof454mwerenotabovethestandards.Theover-standardfrequenciesofthedailyaveragevaluesofPM10andPM2.5attheobservationheightof121mwere0.6%and10.7%,respectively,andtheover-standardamplitudeswere9.0%and24.4%,respectively.Theover-standardfrequencyofthedailyaveragevalueofPM2.5attheobservationheightof454mwas2.0%,andtheover-standardamplitudewas10.4%.Accordingly,itcanbestatedthattheairattheobservationheight454mabovethegrounddidnotreachthesecondarylimitofthenewstandards.Thepollutionwasmostseriousduringwinter,andtheairwasrelativelycleanerduringsummer.Overall,theverticaldistributionsofPM10,PM2.5,andPMldecreasedwithheight.Thelapseratesshowedthefollowingsequence:PM10>PM2.5>PM1,whichindicatesthattheverticaldistributionoffineparticles

简介：Aneigenvaluemethodconsideringthemembranevibrationofwrinklingout-of-planedeformationisintroduced,andthestressdistributingruleinmembranewrinkledareaisanalyzed.Adynamicanalyticalmodelofrectangularshearwrinkledmembraneanditsnumericalanalysisapproacharealsodeveloped.Resultsindicatethatthestressinwrinkledareaisnotuniform,i.e.itislargerinwrinklingwavepeaksalongwrinklesandtwoendsofwrinkleinverticaldirection.Vibrationmodesofwrinkledmembranearestronglycorrelatedwiththewrinklingconfigurations.Therigidityislargerduetotheheavierstressinthepartofwrinklingwavepeaks.Therefore,wavepeaksarealwayslocatedatthenodelinesofvibrationmode.Thevibrationfrequencyobviouslyincreaseswiththevibrationofwavepeaks.

简介：Thestabilitycharacteristicsoflaminarboundarylayersovercompliantwallswasstudiedbythelineartheory.Unlikethepreviousauthors,thecoupledmotionofthefluidandsolidwasrequiredtosat-isfythecontinuityconditionsofboththevelocityandstressattheinterface.Resultsofcalculationsshowthatasthespeedratioordensityratioexceedsacertainthresholdvalue,thetwotypesofunstablewaveswillnolongerbedistinguishable,andthetangentialcomponentofthedisturbancestressisnolongernegligi-ble.Sotheneglectofit,asthepreviousauthorsdid,isunjustified.

简介：IntroductionTungsten-copperalloypowdersareusedinmanyfieldsonaccountofthehighelectricandthermalconductivitiesofcopperandhighmeltingpointoftungsten.W-Cupowders,aspreparedconventionallybymeansofinfiltration,hasthedisadvantageofinhomogeneityinmicrostructure,andaredifficulttoworkwithaftersintering.

简介：Intensiveturbulenceexistsinthewakesofhighspeedtrains,andtheaerodynamicperformanceofthetrailingcarcoulddeterioraterapidlyduetocomplicatedfeaturesofthevorticesinthewakezone.Asaresult,thesafetyandamenityofhighspeedtrainswouldfaceagreatchallenge.Thispaperconsidersmainlythemechanismofvortexformationandevolutioninthetrainflowfield.ArealCRH2modelisstudied,withaleadingcar,amiddlecarandatrailingcarincluded.Di?erentrunningspeedsandcrosswindconditionsareconsidered,andtheapproachesofunsteadyReynold-averagedNavier–Stokes(URANS)anddetachededdysimulation(DES)areutilized,respectively.ResultsrevealthatDEShasbettercapabilityofcapturingsmalleddiescomparedtoURANS.However,forlargeeddies,thee?ectsoftwoapproachesarealmostthesame.Inconditionswithoutcrosswinds,twolargevortexstreetsstretchfromthetrainnoseandinteractstronglywitheachotherinthewakezone.Withthereinforcementoftheground,acomplicatedwakevortexsystemgeneratesandbecomesstrengthenedastherunningspeedincreases.However,thelocationsofflowseparationsonthetrainsurfaceandtheseparationmechanismkeepunchanged.Inconditionswithcrosswinds,threelargevorticesdevelopalongtheleewardsideofthetrain,amongwhichtheweakestonehasnoobviousinfluenceonthewakeflowwhiletheothertwostretchtothetailofthetrainandcombinewiththehelicalvorticesinthetrainwake.Thus,optimizationoftheaerodynamicperformanceofthetrailingcarshouldbeaimingatreducingtheintensityofthewakevortexsystem.

简介：混合象粉末那样的微粒是在包括药品的许多工业的一个重要过程，塑料，家庭产品(例如detergents)并且食物处理。产品的质量取决于他们接着取决于几何设计和操作条件的成分材料混合的度。由于在混合器几何学和小粒的材料之间的相互作用的理解的缺乏，不幸地，有限进步在优化混合器设计被取得了。分离元素方法(DEM)是允许粒子系统被模仿并且混合被预言的一种计算技术。模拟是在困难或昂贵用传统的试验性的途径获得的不同混合器的表演上获得信息的一个有效方法。这里，我们表明DEM怎么能被用来解开流动动力学并且评定在设备的几种不同类型混合。这些设备使用了混合或微粒的使成粒状，当控制的严肃，bladed和高度砍，广泛地被分类。我们也在混合表演和使用DEM测试弗鲁德数字可伸缩是否对预言旋转混合器的规模性能合适探索粒子形状的角色。

简介：Weconductedmeasurementsofblackcarbon（BC）aerosolinJiaxing,ChinaduringautumnfromSeptember26toNovember30,2013.WeinvestigatedtemporalanddiurnalvariationsofBC,anditscorrelationswithmeteorologicalparametersandothermajorpollutants.ResultsshowedthathourlymassconcentrationsofBCrangedfrom0.2to22.0μg/m3,withanaverageof5.1μg/m3.ThediurnaivariationofBCexhibitedabimodaldistribution,withpeaksat07:00and18:00.Themorningpeakwaslargerthantheeveningpeak.ThemasspercentagesofBCinPM2.5andPM10were7.1%and4.8%,respectively.TheabsorptioncoefficientofBCwascalculatedtobe44.4Mm-1,whichaccountedfor11.1%ofthetotalaerosolextinction.BCwasmainlyemittedfromlocalsourcesinsouthwesternJiaxingwhereBCconcentrationsweregenerallygreaterthan11μg/m3duringthemeasurementperiod.CorrelationanalysisindicatedthatthemainsourcesofBCweremotorvehicleexhaust,anddomesticandindustrialcombustion.

简介：Thestudyofbed-loadtransportisofgreatsignificancebothintheoryandinpractice.Thispaperdiscussesthesaltationofbed-loadsolidgrainsinflowingwater.Experimentsandtheoreticanalysishavebeenmadebymeansofhigh-speedphotographingandadvanceddataprocessingtechniquewithacombinedmethodbasedonmechanicalandstatisticaltheories.Itindicatesthatthesaltationisthemainformofthebed-loadtransportunderordinaryflowingconditions.Inthemeantime,takingsuecessivesaltationasthemod-elofbed-loadtransport,systematicanalysishasbeenmadewithregardtothekinematicpropertiesandmechanismofsaltation.ThestatisticalanalysisshowsthattheprobabilitydensityfunctionsoftherelativeheightandlengthofsaltationareinconformitywithΓ-typedistribution,whiletheprobabilitydensityfunc-tionsoftherelativevelocitiesofsaltationareinconformitywiththeGaussiandistribution.

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简介：Measurementofbubblesizeandlocalaveragebubblerisevelocitywascarriedoutinaverticallysinusoidalvibro-fluidizedbed.GlassbeadsofGeldartgroupBparticleswerefluidizedatdifferentgasvelocities,whilethebedwasvibratedatdifferentfrequenciesandamplitudestostudytheireffectsonthebubblebehavior.Thisiscomparedwiththecaseofnovibrationinatwo-dimensionalbedanditisconcludedthatwithvibrationthelocalaveragebubblesize,dbav,decreasessignificantly,especiallyatminimumbubblingvelocity.Theaveragebubblesizeincreasesslightlywithincreasingvibrationfrequencyandamplitude.Thelocalaveragebubblerisevelocityishigherthanthatwithnovibration,thoughwithincreasingvibrationfrequencyandamplitude,itdoesnotchangesignificantly.

简介：Areasonablestrengthcriterionshouldreflectthehydrostaticpressureeffect,minimumprincipalstresseffect,andintermediateprincipalstresseffect.Theformertwoeffectscanbedescribedbythemeridiancurves,andthelastonemainlydependsontheLodeangledependencefunction.Amongthreeconventionalstrengthcriteria,i.e.Mohr–Coulomb(MC),Hoek–Brown(HB),andExponent(EP)criteria,thedifferencebetweengeneralizedcompressionandextensionstrengthofEPcriterionexperienceafirstlyincreasethendecreaseprocess,andtendstobezerowhenhydrostaticpressureisbigenough.Thisisinaccordancewithintrinsicrockstrengthcharacterization.Moreover,thecriticalhydrostaticpressureIccorrespondingtothemaximumdifferenceofbetweengeneralizedcompressionandextensionstrengthcanbeeasilyadjustedbyminimumprincipalstressinfluenceparameterK.So,theexponentfunctionisamorereasonablemeridiancurves,whichwellreflectsthehydrostaticpressureeffectandisemployedtodescribethegeneralizedcompressionandextensionstrength.Meanwhile,threeLodeangledependencefunctionsofLMN,LWW,andLYMH,whichunconditionallysatisfytheconvexityanddifferentialrequirements,areemployedtorepresenttheintermediateprincipalstresseffect.Realizingtheactualstrengthsurfaceshouldbelocatedbetweenthegeneralizedcompressionandextensionsurface,newtrue-triaxialcriteriaareproposedbycombiningthetwostatesofEPcriterionbyLodeangledependencefunctionwithasamelodeangle.Theproposednewtrue-triaxialcriteriahavethesamestrengthparametersasEPcriterion.Finally,14groupsoftriaxialtestdataareemployedtovalidatetheproposedcriteria.Theresultsshowthatthethreenewtrue-triaxialexponentcriteria,especiallytheExponentWillam-Warnkecriterion(EPWW)criterion,givemuchlowermisfits,whichillustratesthattheEPcriterionandLWWhavemorereasonablemeridiananddeviatoricfunctionform,respectively.Theproposednewtrue-tria

简介：Liquidmicro-jets,producedfromgasdynamicvirtualnozzles(GDVNs),areusedassamplecarriersforinteractionwithX-raybeaminserialfemtosecondcrystallography(SFX).Anumericalinvestigationoftheeffectofthefocusinggastypeontheliquidmicro-jetproperties(itslengthandthickness)ispresented.ThestudycomplementsourpreviousresearchontheinfluenceofoperatingconditionsandthenozzlegeometryonGDVNperformance.Theinfluenceofhelium,argon,carbondioxideandnitrogengases(atafixedmassflowrateof1.6×104mg/min)onfocusingpurewaterjet(flowrateof33μl/min)isanalysed.

简介：Mechanicalcharacterizationofsteelframestructureafterfireareanalyzedbasedonfiredynamics,heattransfertheory,structuralmechanics,andfiniteelementtheory.Westudythetemperaturecharacteristicsandmechanicalpropertiesofsteelframestructureunderdifferentfirelocationsandproposeasafetyevaluationmethod.Wealsoanalyzedamagelevelofmainframecomponents,maximumtemperatureoffire,thermalcharacteristicsofframecomponents,firingduration,etc.toprovideusefulinformationforfireresistancedesignofthesteelframestructureandpost-disastersafetyevaluation.

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简介：Insulatorsonhigh-voltageUansmissionlinesarealmosttheonlyman-madestructuresontheEarth'ssurfaceintendedforlong-termoperationunderstrongelectricfields.AftersamplesofnaturalcontaminantparticleswerecollectedfrominsulatorsurfacesinChina,itwasfoundthattheparticlediameterdistribution(PDD)wasmainlyconcentratedinthe5-50μmrange.Toanalyzethestatisticalcharacteristicsoftheseparticles,thisworkstudiesthephysicalprocessesofparticlecollisionandadhesionusingthetheoriesofhydrodynamicsandcollisiondynamics.Thephysicalmodelconsiderscouplingofthefluidfieldandtheelectricfield,introducesanadhesioncriterion,andestablishesaparticleandsurfacecollisionmodel.Theeffectsofrelativehumidity,windspeed,aerodynamicshape,electricfieldtype,andelectricfieldstrengthonparticleadhesionwereanalyzed.Theresultsshowthattherelativehumidityandwindspeedhaveverysignificanteffectsandtheinfluencesoftheelectricfieldtypeandtheelectricfieldstrengthareobvious,buttheinfluenceoftheaerodynamicshapeisrelativelyweak.Thesimulationresultssupportthestatisticalcharacteristicsdeterminedinthiswork.Thephysicalmodelestablishedhereprovidesreferencevaluesforstudyoftheadhesioncharacteristicsofparticlesonsurfacesunderelectricfields.

简介：ThisstudyinvestigatesthecorrelationbetweenPM10andmeteorologicalfactorssuchaswindspeed,atmosphericvisibility,dewpoint,relativehumidity,andambienttemperatureduringabrownhazeepisode.InordertoidentifythepotentialsourcesofPM10duringbrownhazeepisode,respirableparticulatematter(PM10)wascollectedduringbothnon-hazedaysandhazedaysandfurtheranalyzedformetallicelements,ionicspecies,andcarbonaceouscontents.Amongthem,ionicspeciescontributed45-64%toPM10,whilemetallicelementscontributed7-21%toPM10whichwassmallerthantheotherchemicalconstituents.TheaverageOC/ECratio(42)inhazedayswasaboutthreetimesoftheaverageOC/ECratio(14)innon-hazedays.Byusingchemicalmassbalance(CMB)receptormodel,themajorsourceswereapportioned,includingtraffics,incinerators,coalcombustion,steelindustry,petrochemicalindustry,andsecondaryaerosols,etc.ThecontributiontoPM10concentrationofeachsourcewascalculatedforallthesamplescollected.TheresultsshowedthatcoalcombustionwasthemajorsourceofPM10innon-hazedaysandsecondaryaerosolswerethemajorsourceinhazedays,followedbypetrochemicalindustry,incinerators,andtraffics,whileothersourceshadnegligibleeffect.