简介:AnanalysisispresentedwithmagnetohydrodynamicsnaturalconvectiveflowofaviscousNewtonianfluidsaturatedporousmediuminaverticalslot.TheflowintheporousmediahasbeenmodeledusingtheBrinkmanmodel.Thefully-developedtwo-dimensionalflowfromcappedtoopenendsisconsideredforwhichacontinuumofsolutionsisobtained.Theinfluenceofpertinentparametersontheflowisdelineatedandappropriateconclusionsaredrawn.Theasymptoticbehaviourandthevolumefluxareanalyzedandincorporatedgraphicallyforthethree-parameterfamilyofsolution.
简介:ThispaperinvestigatestheunsteadyhydromagneticCouettefluidflowthroughaporousmediumbetweentwoinfinitehorizontalplatesinducedbythenon-torsionaloscillationsofoneoftheplatesinarotatingsystemusingboundarylayerapproximation.ThefluidisassumedtobeNewtonianandincompressible.Laplacetransformtechniqueisadoptedtoobtainaunifiedsolutionofthevelocityfields.Suchaflowmodelisofgreatinterest,notonlyforitstheoreticalsignificance,butalsoforitswideapplicatio...
简介:Basedonthetheoryofcomplexfunctionandtheprincipleofhomogenization,harmonicdynamicsstressofaradiallyinfiniteinhomogeneousmediumwithacircularcavityisinvestigated.Duetothesymmetry,wavevelocityisassumedtohavepower-lawvariationintheradialdirectiononly,andtheshearmodulusisconstant.TheHelmholtzequationwithavariablecoefficientisequivalentlytransformedintoastandardHelmholtzequationwithageneralconformaltransformationmethod(GCTM).Thedisplacementsandstressfieldsareproposed.Numericalresultsshowthatthewavenumberandtheinhomogeneityparameterofthemediumhavesignificanteffectsonthedynamicstressconcentrationaroundthecircularcavity.Thedynamicstressconcentrationfactor(DSCF)becomessingularwhentheinhomogeneityparameterofmediumisclosetozero.
简介:Nano-sizedhexagonalmagnesiumhydroxide(Mg(OH)2)withgooddispersibilitywassynthesizedbyadoubleinjection-hydrothermalmethod,utilizingpolyvinylpyrrolidone(PVP)asanadditiveandwithoptimizedprocessingparameters.SEMandBETanalysisshowedthatthemeanparticlesizeandspecificsurfaceareaoftheMg(OH)2particleswere174nmand50.77m2/g,respectively.TheFT-IRspectraandtheXRDpatternsshowedthatPVPwasadsorbedonthesurfaceoftheMg(OH)2crystal,thuseffectivelylimitingparticleagglomerationandhinderingcrystalgrowthalongthe(101)plane.TGAshowedadecreaseinthedecompositiontemperatureandanincreaseintheweightlossoftheMg(OH)2particlesduetoadditionofPVP.
简介:TheDonnelltheoryofshellwasappliedtodescribeshellmotion.Theinnerandoutershellswerestiffenedbytransversecomponents.Usingdeformationharmoniousconditionsoftheinterface,theeffectsofstiffenersweretreatedasreverseforcesandmomentsonthedoublecylindricalshell.Intheacousticfieldproducedbyvibrationandsoundradiationofthedoubleshell,thestructuredynamicequation,Helmholtzequationinthefluidfieldandthecontinuityconditionsofthesurfaceoffluid-structurecomposethevibrationequationcoupledbythesound-fluid-structure.Theextractofacousticpressurecomesdowntotheextractofcouplingvibrationequation.Thenearfieldacousticpressurecanbesolveddirectlybycomplicatedcalculationalmethods.
简介:Alginatebeads,oftenusedforcontrolledreleaseofenzymesanddrugs,areusuallyproducedbysprayingsodiumalginateliquidintoagellingagentusingmechanicalvibrationnozzleorairjet.Inthisworkanalternativemethodofelectro-spraywasemployedtoformdropletswithdesiredsizefromahighlyviscoussodiumalginatesolutionusingconstantDCvoltage.Thedropletswerethencuredinacalciumchloridesolution.Themainobjectivewastoproducemono-sizedbeadsfromsuchahighlyviscousandnon-Newtonianliquid(1000-5000mPas).Theeffectsofnozzlediameter,flowrateandconcentrationofliquidonthesizeofthebeadswereinvestigated.Amongtheparametersstudied,voltagehadapronouncedeffectonthesizeofbeadsascomparedtoflowrate,nozzlediameterandconcentrationofalginateliquid.Thesizeofbeadswasreducedtoaminimumvaluewithincreasingthevoltageintherangeof0-10kV.Attheearlystagesofvoltageincrease(i.e.uptoabout4kV),therateofsizereductionwasrelativelylow,whilethedrippingmodedominated.However,inthemiddlepartoftherangeofappliedvoltage,wheretherateofsizereductionwashigh(i.e.about4-7kV),anunstabletransitionoccurredbetweendrippingandjetting.Attheendpartoftherange(i.e.7-10kV)jetmodeofspraywasobserved.Increasingtheheightoffallofthedropletswasfoundtoimprovethesphericityofthebeads,becauseoftheincreasedtimeofflightforthedroplets.Thiswasespeciallyidentifiableathigherconcentrationsofthealginateliquid(i.e.3w/v%).
简介:InChinamorethantwo-thirdsofavailablecoalreservesareinaridareas,where,tobeneficiatetherun-of-minecoal,thereisnotenoughwaterresourcerequiredbyconventionalprocessing.DevelopingefficientdrybeneficiationtechnologyisofgreatsignificanceforefficientcoalutilizationinChina,notablythecleancoaltechnology(CCT).Thedrycoalbeneficiationtechnologywithair-densemediumfluidizedbedutilizesair-solidsuspensionasbeneficiatingmediumwhosedensityisconsistentforbeneflciation,similarinprincipletothewetdensemediumbeneficiationusingliquid-solidsuspensionasseparatingmedium.Theheavyportioninfeedstockwhosedensityishigherthanthedensityofthefluidizedbedwillsink,whereasthelighterportionwillfloat,thusstratifyingthefeedmaterialsaccordingtotheirdensity.Inordertoobtainefficientdryseparationinair-densemediumfluidizedbed,stablefluidizationwithwelldispersedmicro-bubblesmustbeachievedtoensurelowviscosityandhighfluidity.Thepurebuoyancyofbeneficiationmaterialsplaysamainroleinfluidizedbed,andthedisplaceddistributioneffectshouldberestrained.Thedisplaceddistributioneffectsincludeviscositydisplaceddistributioneffectandmovementdisplaceddistributioneffect.Theformeriscausedbyviscosityofthefluidizedbed.Itdecreaseswithincreasingairflowvelocity.Movementdisplaceddistributioneffectwillbelargewhenairflowrateistoolowortoohigh.Ifmediumparticlesizedistributionandairflowarewellcontrolled,bothdisplaceddistributioneffectscouldbecontrolledeffectively.Abeneficiationdisplaceddistributionmodelmaybeusedtooptimizebeneficiationoffeedstockwithawideparticlesizedistributionandmultiplecomponentsinthefluidizedbed.Therheologicalcharacteristicsoffluidizedbedswerestudiedusingthefallingspheremethod.ExperimentalresultsindicatedthatthefluidizedbedbehavesasaBinghamfluid.Theplasticviscosityandyieldstresscanbe
简介:Aneffectivemethodisdevelopedandusedtoinvestigatethean-tiplaneproblemofarigidlineinaconfocalellipticinhomogeneityembeddedinaninfinitemedium.Theanalyticalsolutionisobtained.Theproposedmethodisbasedupontheuseofconformalmappingandthetheoremofanalyticcontinuation.Specialsolutionswhichareverifiedbycomparisonwithexistingonesareprovided.Finally,thecharacteristicsofstresssingularityatthetipoftherigidlineinhomogeneityareanalyzedandtheextensionforcesforthecrackandtherigidlineinhomogeneityarederived.
简介:当在ethanolwater的开始者混合了溶剂,有为播种乳剂聚合要用作种子的375nm的直径的聚苯乙烯(PSt)microspheres用钾persulfate(KPS)经由乳剂聚合被准备。有丙烯腈的苯乙烯(圣)的使乳化免费的播种乳剂copolymerization(一)被执行面对poly(乙烯乙二醇)是的monomethoxymonomethacrylate(PEGm)macromonomer反应stabilizer和2,2-azobisisobutyronitrile(AIBN)是poly获得亚微米大小的PEGm接枝的开始者(styrene-co-acrylonitrile)(PEGm-g-PSAN)合成粒子与唯一的形态学。扫描电子显微镜学(SEM)显示了那圣并且一一起形成不平常的形态学贡献。圣的集中并且一,显著地增加方法的全部的单体集中,开始者类型和单体影响了合成聚合物粒子的形态学。
简介:Ananalyticalmodelisdevelopedtostudythesurfaceeffectsonthevibrationbehaviorincludingthenaturalfrequencyandthecriticalflowvelocityoffluid-conveyingnanotubesembeddedinanelasticmedium.TheeffectsofsurfaceelasticityandresidualsurfacestressareaccountedthroughthesurfaceelasticitymodelandtheYoung-Laplaceequation.AWinkler-typefoundationisemployedtomodeltheinteractionofnanotubesandthesurroundingmedium.Theresultsshowthatthesurfaceeffectshavemoreprominentinfluencesonthenaturefrequencywithsmallernanotubethickness,largeraspectratioandlargerelasticmediumconstants.Bothsurfacelayersandtheelasticmediumenhancethestabilityofnanotubes.Thisstudymightbehelpfulfordesigningthefluid-conveyingnanotubedevicesinNEMSandMEMSsystems.
简介:ThesolutionsofGreen'sfunctionaresignificantforsimplificationofproblemonatwo-phasesaturatedmedium.UsingtransformationofaxisymmetriccylindricalcoordinateandSommerfeld'sintegral,superpositionoftheinfluencefieldonafreesurface,authorsobtainedthesolutionsofatwo-phasesaturatedmediumsubjectedtoaconcentratedforceonthesemi-space.
简介:Anumericalstudyofanon-Darcymixedconvectiveheatandmasstransferflowoveraverticalsurfaceembeddedinaporousmediumundertheefectsofdoubledispersion,melting,andthermalradiationisinvestigated.Thesetofgoverningboundarylayerequationsandtheboundaryconditionsistransformedintoasetofcouplednonlinearordinarydiferentialequationswiththerelevantboundaryconditions.ThetransformedequationsaresolvednumericallybyusingtheChebyshevpseudospectralmethod.Comparisonsofthepresentresultswiththeexistingresultsintheliteraturearemade,andgoodagreementisfound.Numericalresultsforthevelocity,temperature,concentrationprofiles,andlocalNusseltandSherwoodnumbersarediscussedforvariousvaluesofphysicalparameters.
简介:Theinfluenceofinitialstrainstateonthedynamicresponseofanendbearingpileembeddedinisotropicsaturatedsoilisinvestigatedthroughthelinearizedtheoryofsmallelasticperturbationsuperposedonlargelystressedbodies.Thegoverningequationsforsoil,basedonBiot’sporoelasticitytheory,arederivedinthecylindricalcoordinates,andthepileismodeledbyusingtheone-dimensionalelastictheory.Theanalyticalsolutionsofpileimpedance,frequencyresponseofbothtwistangleandtimehistoryofvelocityresponseareobtainedbyusingofseparationofvariablestechnique.Finally,aparametricstudyoftheinfluenceofinitialstrainsonthetorsionalimpedance,twistangle,andvelocityresponseatthetopofthepileiscarriedout.
简介:Thispaperstudiesthethermal-diffusionanddiffusionthermo-effectsinthehydro-magneticunsteadyflowbyamixedconvectionboundarylayerpastanimpermeableverticalstretchingsheetinaporousmediuminthepresenceofchemicalreaction.Thevelocityofthestretchingsurface,thesurfacetemperature,andtheconcentrationareassumedtovarylinearlywiththedistancealongthesurface.Thegoverningpartialdifferentialequationsaretransformedintoself-similarunsteadyequationsusingsimilaritytransformationsandsolvednumericallybytheRunge-Kuttafourthorderschemeinassociationwiththeshootingmethodforthewholetransientdomainfromtheinitialstatetothefinalsteadystateflow.Numericalresultsforthevelocity,thetemperature,theconcentration,theskinfriction,andtheNusseltandSherwoodnumbersareshowngraphicallyforvariousflowparameters.Theresultsrevealthatthereisasmoothtransitionofflowfromunsteadystatetothefinalsteadystate.Aspecialcaseofourresultsisingoodagreementwithanearlierpublishedwork.