学科分类
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72 个结果
  • 简介:Lithium-aluminum-cobalt-nickeloxideLiAlxCoyNi1xyO2particles,generallyusedascathodeoflithiumbattery,werepreparedbychemicalcoprecipitationfromanaqueoussolutionofLiOH,Al(NO3)3,Co(NO3)2andNi(NO3)2withNH4OH.XRD,SEMandFTIRwereusedtoexaminetheeffectofnickelcontentontheproduct.FTIRpatternsshowedthatincreaseinnickelcontentdecreasedtheabsorptionstrengthofthepeakofspinelstructureoftheproduct,attributedtotheoccupationbynickelinthealuminumsites.Particlesizeandelectricalpropertiesofthelithium-aluminum-cobalt-nickeloxide(abbreviatedasLACNO)particleswerealsodetermined.

  • 标签: LiAlxCoyNi1-x-yO2 Chemical coprecipitation Particle size Electrical
  • 简介:The(2+1)-dimensionalBKPequationintheHirotabilinearformisstudiedduringthiswork.WronskianandGrammiantechniquesareappliedtotheconstructionofWronskianandGrammiansolutionsofthisequation,respectively.ItisshownthatthesesolutionscanbeexpressedasnotonlyPfaffiansbutalsoWronskiansandGrammians.

  • 标签: Wronski行列式 KP方程 双线性形式 可表
  • 简介:信息融合系统的开发需要规范化。在分析信息融合系统工程方法的基础上,对信息融合系统的设计过程及设计产品描述方法进行了研究,分别研究了应用体系结构设计、系统体系结构设计及数据融合节点设计,以及各自的设计产品的描述方法,并提出了相应设计结果的描述元模型。实践证明,规范化有助于提高信息融合系统质量以及开发效率。

  • 标签: 信息融合系统工程 设计过程 描述方法 元模型
  • 简介:针对一种新型水下气液两相冲压发动机,综合考虑了湍流效应、液两相之间的拖曳作用及传热与传质,利用计算流体力学方法研究了液两相冲压发动机内流场的流动特性随发动机工作条件的变化规律,重点研究了气蚀效应对发动机工作性能的影响.主要结论为:当航行速度大于32m/s,液两相冲压发动机人口附近会产生气蚀并造成严重的总压损失,导致扩张段下游产生流动分离,此时发动机无法产生正推力;通过增大气体质量流率,液两相冲压发动机内流场的压力将会随之升高,气蚀效应被抑制;提高注入发动机气体的温度,发动机的推力及比冲均增大,但是发动机效率急剧降低.

  • 标签: 水下推进 冲压发动机 气蚀 两相流 数值模拟
  • 简介:Thecoordinationpolymer,(Nd(H2O)5)2(2,6-AQDS)3·2H2Owhere2,6-AQDS=2,6-anthraquinonedisulfonate,hasbeensynthesisedviaahydrothermalroute.Structurally,itconsistsoflayersofmonomericNdpolyhedrawhicharelinkedby2,6-AQDSanionsformingapolymeric,three-dimensionalnetwork.EachNdatomisninecoordinate,bondingtofivewatermoleculesandtofouroxygenatomsfromfour2,6-AQDSanionswhichinturnpillarthelayersbybridgingtwoNdatomsinonelayer,andcoordinatingtoasingleNdintheother.

  • 标签: 配位聚合物 水热法合成 晶体结构 络阴离子 氧原子
  • 简介:NanocrystallineSnO2wassynthesizedbydirectmixingandgrindingofSnCI4-5H2OandNaOHatroomtemperature,followedbycalcinationatdifferenttemperaturesfordifferenttimesinair.ProductsampleswerecharacterizedbyX-raydiffractionandtransmissionelectronmicroscope,revealingthattheamorphousprecursorSnO2wastransformedtocrystalsat200℃for3h,andthattheaverageparticlesizeincreaseduponraisingthecalciningtemperatureorprolongingthecalciningtime.Themechanismofthephasetransformationoftheproductsisdiscussed.

  • 标签: 二氧化锡纳米晶体 纳米材料 固态反应 焙烧 X射线衍射分析 透射电子显微镜分析
  • 简介:连贯的多角形的粒子的二维的分离元素模型(DEM)模拟被开发了估计点来源颤动的利益在楔形的hoppers导致流动。使用的particleparticle相互作用模型基于一个多接触原则。没有颤动,学习的第一部分在严肃下面调查了粒子分泌物决定批评的孔尺寸(Bc)就作为粒子形状的功能支撑流动。多角形形状的粒子比圆形的粒子需要一个更大的孔,这被显示出。当粒子顶点的数字增加,Bc减少,这也被显示出当粒子顶点的数字增加。圆形的粒子的增加以一种线性方式支持多角形的流动。学习的第二部分证明那颤动能提高流动,有效地减少Bc。模型表明了震荡器地点(高度)的重要性,与在提高的以前的连续统模型结果,和颤动振幅一致流动。

  • 标签: 动力效应模型 固体 振动 仿真
  • 简介:Uniformlysizedα-Fe2O3hexagonalplateletsweresynthesizedbyahydrothermalprocessusingFe(OH)3suspensionandlargeamountofNaOH.ThereactionproductswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),selectedareaelectrondiffraction(SAED),andavibratingsamplemagnetometer(VSM).Theresultsshowthatthehexagonalplateletsarefine,monodisperseandconsistingofsingle-crystals.Themagnetichysteresis(M-H)curveofthesamplesmeasuredatroomtemperatureindicatesthattheα-Fe2O3micro-plateletsexhibitferromagneticbehaviorswithrelativelylowcoercivity.

  • 标签: Fe2O3 六角片状 单分散 水热法合成 振动样品磁强计 扫描电子显微镜
  • 简介:Commerciallyavailablelatticescontainvariouskindsofmorphologicalimperfectionswhichresultingreatdegradationinlattices’mechanicalproperties,therefore,toobtainimperfectioninsensitivelatticestructureisobviouslyapracticalresearchsubject.Hierarchicalstructurematerialswerefoundtobeaclassofpromisinganti-defectmaterials.Thispaperbuildshierarchicallatticebyaddingsoftadhesiontolattice’scelledgesandnumericalresultsshowthatitsimperfectionsensitivitytomissingbarsisminorcomparedwiththeclassiclattice.Softadhesionwithappropriatepropertiesreinforcecelledge’sbendingstiffnessandthusreducethebendingdeformationinlatticecausedbymissingbarsdefect,whichisconfirmedbystatisticalanalysisofnormalizednodedisplacementsofimperfectlatticesunderhydrostaticcompressionandshearloads.

  • 标签: 敏感性 缺陷 晶格结构 二维 结构材料 力学性质
  • 简介:Inthisarticle,low-pressurecontrolmethodsforacombinedarcsubmergednanoparticlesynthesissystem(ASNSS)wasproposedanddevelopedforTiO2nanoparticlefabrication.Thephotocatalyticreactioniscarriedoutinaphotochemicalreactor.TheUVlightisobtainedfromUV-lampswithwavelengthof(253.7±0.8)nm.TheUV-Visspectrometryisusedtomonitortheabsorbancespectraofmethyleneblueasafunctionofilluminationtime.ExperimentalresultsshowthattherateconstantofphotocatalyticreactionofTiO2nanoparticlesformethyleneblueis0.0365min^-1.Thesurfaceadsorptionplaysanimportantroleinthedecompositionofmethyleneblue.ExperimentalresultsindicatethattheTiO2nanoparticlefluidpossessesexcellentphotocatalyticactivityinphotodegradationofmethyleneblue.

  • 标签: 二氧化钛 纳米颗粒流 光催化性质 ASNSS
  • 简介:目前,随着相关项目研究的不断推进,如何在高Reynolds数下研究其对气动光学效应的影响成为重要命题.通过设计变Reynolds数气动光学效应实验平台,模拟的单位Reynolds数可以在7.2×10^6-2.2×10^8m^-1范围内变化.搭建的基于背景纹影(backgroundorientedschlieren,BOS)的波前测试系统可以达到6ns的时间分辨率.此系统测量的平凸透镜波前结果表明:实验测量结果与理论计算结果的误差在±4%以内.通过测量9种不同Reynolds数下的超声速膜瞬态波前数据,分析结果表明:在高Reynolds数条件下,Reynolds数对于超声速膜气动光学效应的影响比较明显,通过对实验数据进行函数拟合发现OPDrmsRe088,与推导结果OPDrmsRe09十分接近;利用小波分析方法研究了高Reynolds数条件下气动光学效应沿流向的分布特征,发现OPDrms的低频部分(信号的主体)先降低后升高,但是高频部分的震荡幅度先升后降.分析认为OPD的低频部分主要受到流场整体结构的影响,而高频部分更多地受到涡的空间分布影响.

  • 标签: 气动光学 超声速气膜 REYNOLDS数 背景纹影 小波分析
  • 简介:Thereisaneedtostandardizemethodsassociatedwiththedispersionofnanomaterialsinnano(eco)toxicologicalinvestigations.Thefirststeptowardthisgoalistounderstandthedegreeofvariabilitythatexistsinnanomaterialdispersionspreparedbyusingdifferentprotocols.Usingtwocasestudies,thedegreeofvariabilityinTiO2nanomaterialdispersionswasassessedbydifferentialcentrifugalsedimentation(DCS)methods.Casestudy1addressesthevariabilitythatarisesfromvariationswithinoneprotocol,investigatingtheeffectsofdispersionaging,sonicationexposuretime,sonicationinthepresence/absenceofanicebath,materialsubsampling,particleconcentrationandhavingapre-wettingstep.Casestudy2addressesthevariabilitybetweenfourdifferentprotocolsdevelopedthroughpastresearchactivitiesandprojects.Theresultsindicatethatthereisalargedegreeofvariability(relativestandarddeviation(RSD)ofmeanparticlediameter=26%)inthedispersionofTiO2nanomaterialsbetweenthefourdifferentprotocolsstudiedandthatseveralstepsinadispersionprotocolarepotentialsourcesofvariation,withfinalparticleconcentrationbeingthemostsignificant.Theimplicationofthisstudyisclear:forthepurposeofdatacomparability,thereisaneedtoprovidetheexactdetailsofallstepsinvolvedinadispersionprotocol.

  • 标签: 分散体 协议 粒度分布 TIO2 纳米材料 相对标准偏差
  • 简介:Laminatedcompositematerialsarewidelyimplementedinseveralengineeringconstructions.Foritsrelativelightweight,thesematerialsaresuitableforaerospace,military,marine,andautomotivestructuralapplications.Toobtainsafeandeconomicalstructures,themodellinganalysisaccuracyishighlyrelevant.Sincemeshlessmethodsintherecentyearsachievedaremarkableprogressincomputationalmechanics,thepresentworkusesoneofthemostflexibleandstableinterpolationmeshlesstechniqueavailableintheliterature—theRadialPointInterpolationMethod(RPIM).Here,a2Dapproachisconsideredtonumericallyanalysecompositelaminatedbeams.Boththemeshlessformulationandtheequilibriumequationsrulingthestudiedphysicalphenomenonarepresentedwithdetail.Severalbenchmarkbeamexamplesarestudiedandtheresultsarecomparedwithexactsolutionsavailableintheliteratureandtheresultsobtainedfromacommercialfiniteelementsoftware.Theresultsshowtheefficiencyandaccuracyoftheproposednumerictechnique.

  • 标签: RADIAL POINT interpolators RPIM LAMINATED BEAM
  • 简介:在组成的部件之间的有瑕疵的结合能极大地影响合成结构的性质。处于2Dfibrereinforced的问题产生的有瑕疵的接口的不同类型的asymptotic分析合成材料被建议。执行学习基于管理biharmonic问题的asymptotic减小进二个泛音问题。所有答案在一种关上的分析形式被获得。获得的结果能被用于撤退和pushout测试的计算,以及为合成材料的破裂的调查。

  • 标签: 复合材料界面 纤维增强 2D 复合材料结构 双调和问题 组成成分
  • 简介:ThecaptureoforthophosphatesandtotalphosphorusfromthePudongCanalriverinthePudongDistrictofShanghaibyTiO2nanoparticlesisstudiedusingarotatingphotoreactorandthenano-TiO2photocatalystDegussaP25.TheeffectsofUVirradiationintensityinarangeof20-74mW/cm2.theloadingoftheTiO2nanoparticlesinarangeof0.05-0.1g/L,irradiationtimeupto4h,andpHvaluesinarangeof2-10.5onthecaptureefficiencyareinvestigated.TheresultsshowthatthecaptureoforthophosphatesandtotalParesignificantlyenhancedbyUVirradiation;ataloadingof0.1g/Landanirradiationintensityabove36mW/cm2,orthophosphatesandtotalphosphorusarerapidlycapturedbyTiO2nanoparticles,causinganobservedreductionfrom0.4mg/Ldownto0.02mg/L.pHvaluesinarangeof2-10.5havelittleeffectonthecaptureefficiencyoforthophosphatesandtotalphosphorus.

  • 标签: 纳米二氧化钛光催化剂 紫外光照射 捕获 总磷 二氧化钛纳米粒子 地表水
  • 简介:Hierarchicalsea-urchin-shapedmanganeseoxidemicrospheresweresynthesizedviaatacilemetnoabasedonthereactionbetweenKMnO4andMnSO4inHNO3solutionat50C.Theaveragediameterofthemicrospheresis850nm.Themicrospheresconsistofacoreofdiameterof800nmandnanorodsofwidth50nm.Thenanorodsexistattheedgeofthecore.TheBrunauer-Emmett-Tellersurfaceareaofthesea-urchin-shapedmicrospheresis259.4m2/g.Apossibleformationmechanismofthehierarchicalsea-urchin-shapedmicrospheresisproposed.Thetemperaturefor90%conversionofbenzene(T90%)onthehierarchicalurchin-shapedMnO2microspheresisabout218℃.

  • 标签: 催化氧化 MNO2 型综合 平均直径 二氧化锰
  • 简介:ZrO2nanopowdersbasedstearicacidphasechangematerials(PCMs)werepreparedbyhigh-energymilling.Theconceptofheatcapacityfactor(HCF)wasusedtoanalyzethethermalpropertiesofthematerials.TheheatstoragepropertyofPCMs,containingthesamecontentofstearicacid(23%bymass)inthestartingmaterialsbutsynthesizedbydifferenttechnicalprocesses,wasinvestigatedbyusingHCF.Itwasfoundthattherewerevastinfluencesofdifferentdispersantsontheheatcapacity.Thesamplespreparedwithchloroformprovidedthebestheatstorageabilityinallsamplestested.

  • 标签: 相变材料 纳米粉体 硬脂酸 氧化锆 基础研究 蓄热性能