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500 个结果
  • 简介:Thefullpotentiallinearizedaugmentedplanewave(FLAPW)methodisusedtostudythecrystalstructureandelectronicstructurepropertiesofPbFeo.5Nbo.5O3(PFN).Theoptimizedcrystalstructure,densityofstates,bandstructureandelectrondensitydistributionhavebeenobtainedtounderstandtheferroelectricbehaviourofPFN.TheanalysisresultofthedensityofstatesshowsthereisanobviouschangeofNbdstatesintheparaelectric-to-ferroelectricphasetransition.ThepolarizationresultshowsthatthecontributiontoferroelectricityofNbatomsislargerthanthatofFeatoms.InferroelectricphasethereisahybridizationofFed-OpandNbd-OpinferroelectricPFN.Thisisconsistentwiththeresultoftheelectronicbandstructure.Thishybridizationisresponsibleforthetendencytoitsferroelectricity.

  • 标签: 电子结构 PbFe0.5Nb0.5O3 钙钛矿 FLAPW法 晶体结构
  • 简介:Synthesis,structureandmagneticpropertiesofRudopedperovskitestructuredmanganiteLa0.5Sr0.5MnO3wereinvestigatedexperimentally.Ahydrothermalmethodwasusedforthepreparationofthesamples.Ahigh-temperatureannealingprocesswasalsoemployedtomakeacomparison.AslightlyenhancementoftheunitcellvolumewasobservedwiththeincreaseofRuconcentration.Scanningelectronmicroscopyshowsthatthematerialsaremadeupofcube-shapedparticleswithdimensionofseveralmicrometers.Importantly,itisfoundthatboththeCurietemperatureTCandsaturationmomentcanbereducedbyRudoping.ThevalueofcoercivefieldisnotaffectedbytheintroductionofRu.

  • 标签: La0.5Sr0.5MnO3 HYDROTHERMAL synthesis RU DOPING CURIE
  • 简介:Effectofvelocityjumpandtemperaturejumpontheheatandmomentumtransferinmicro-domainsisdiscussedindetail.Asimulationaidedbylocallyfullydevelopedassumptionisdevelopedtoexplaintheexperimentalresultsdifferentfromthosepredictedbyconventionaltheory.Heattransferinmicro-channelsundertheuniformheatfluxisalsoanalyzed.Itisfoundthatvelocity-jumpandtemperature-jumphaveanoppositeinfluenceandNusseltnumberhasagreatervaluewhentheKnudsennumberisverysmall,WiththeincreasingofKnudsenNumber,Nussqltnumberbecamesmallerthan8.24.

  • 标签: 热传导 动量传输 微型通道
  • 简介:这份报纸报导巨浪试验性、理论学习发生在原型一台极端微离心压缩机。作为第一步,10次缩放有40公里一台极端微离心压缩机模型外部直径被设计并且生产。为有B参数几不同价值巨浪短暂行为详细试验性调查被执行。试验性结果在巨浪期间与非线性lumped参数理论获得以便为微离心压缩机验证理论巨浪模型有效性那些相比。作为结果,巨浪相当不同行为在实验并且在分析为B不同价值出现了。关键词微离心压缩机-澎湃-lumped参数模型CLC数字TK474.8+2

  • 标签: 微离心压缩机 汹涌 集中参量模型 外直径
  • 简介:首次制备出粉末微晶BaCl0.5Br0.5F:Sm2+红色发光材料,并测量了其低温光谱。发现其谱线宽度与BaClF:Sm2+相比较有了约十倍左右非均匀增宽,而且相应于5D0,1,2→7F0,1谱线由两个峰间距分别为15cm-1,65cm-1谱线构成,峰间距只与基态7F0和7F1有关。W.Lenth&W.E.Morener[1]讨论了光子门光谱烧孔作为频率微区光学记录理论和应用可能性。对于长存光谱烧孔,可以进行二进制数据存储与改写。该技术为实现大容量、高速度光学计算机应用提供了新前景。在这方面已经有了不少研究工作[2~6]。为提高存储容量,需使光谱线非均匀增宽,以提供更多光谱烧孔可能性。为此目的,首次制备出粉末微晶BaCl0.5Br0.5F:Sm2+红色发光材料,并测量了其低温光谱,并将其与BaClF:Sm2+低温光谱进行了比较分析。

  • 标签: BaClF:Sm2+ 发光材料 低温光谱
  • 简介:Inthiswork,weinvestigatethemethodstoimprovetheperformanceofthesweptsourceat1.0μmbasedonapolygonscanner,includingin-cavityparametersandboosterstructuresoutofthecavity.Thethreein-cavityparametersarethecavitylength,therotatingspeedofthepolygonscanner,andthein-cavityenergy.Withthedecreaseofcavitylength,thespectrumbandwidthbecomeswiderandthedutycyclebecomeshigher.Withtheincreaseoftherotatingspeedofthepolygon,thespectrumbandwidthbecomesnarrower,andthedutycyclebecomeslowerbuttherepetitionratebecomeshigher.Withmoreenergyin-cavity,thespectrumbandwidthbecomeswiderandthedutycyclebecomeshigher.Theboosterstructuresincludethebufferedstructure,secondaryamplifier,anddual-semiconductoropticalamplifierconfiguration,whichareusedtoincreasethesweepfrequencyto86kHz,theoutputpowerto18mW,andthetuningbandwidthto131nm,respectively.

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  • 简介:点火分叉分析和催化燃烧在扑灭一突然微隧道被执行,laminar模型作为流动模型合并了。横向Thiele模量和滞留时间平方被用作分叉参数。点火和扑灭行为上不同参数影响被调查。所有这些参数在点火和扑灭分叉行为上有大效果在,这被显示出突然微隧道。燃烧分叉行为上流动模型效果也被分析。结果证明与扁平速度侧面模型比较,为laminar模型案例,点火温度和燃烧扑灭更高,不稳定多重答案区域更大。

  • 标签: 催化燃烧 分叉理论 热学 热处理
  • 简介:Weinvestigatethedynamiccrystallizationprocessesofcolloidalphotoniccrystals,whicharepotentiallyinvaluableforsolvinganumberofexistingandemergingtechnicalproblemsinregardstocontrolledfabricationofcrystals,suchassizenormalization,stabilityimprovement,andaccelerationofsynthesis.Inthispaper,wereportsystematichigh-resolutionopticalobservationofthespontaneouscrystallizationofmonodispersepolystyrene(PS)micro-spheresinaqueoussolutionintoclose-packedarraysinastaticlineopticaltweezers.Theexperimentsdemonstratethatthecrystalstructureismainlyaffectedbytheminimumpotentialenergyofthesystem;however,thecrystallizationdynamicscouldbeaffectedbyvariousmechanical,physical,andgeometricfactors.Thecomplicateddynamictransformationprocessfrom1Dcrystallizationto2Dcrystallizationandthecreationandannihilationofdislocationsanddefectsviacrystalrelaxationareclearlyillustrated.Twomajorcrystalgrowthmodes,theepitaxygrowthpatternandtheinsertedgrowthpattern,havebeenidentifiedtoplayakeyroleinshapingthedynamicsofthe1Dand2Dcrystallizationprocess.Theseobservationsofferinvaluableinsightsforin-depthresearchaboutcolloidalcrystalcrystallization.

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  • 简介:在这篇论文,表演和传统类型声学噪音,微多片扇子试验性地并且数字地被调查,到为居民情形优化扇子说明。声学噪音水平减少,但是效率随impeller片数字增加稍微败坏。而且,声学噪音随在impeller插头和涡囊舌头之间距离增加减少,在随输入增加和扇子效率恶化伴随。

  • 标签: 鼓风机 热风 扇子 研究
  • 简介:PalladiumcatalystsaresupportedonTiO2,ZrO2,Al2O3,Zr0.5Al0.5O1.75andTiO2-Zr0.5Al0.5O1.75preparedbyco-precipitationmethod,respectively.CatalyticactivitiesformethaneandCOoxidationareevaluatedinagasmixturethatsimulatedtheexhaustfromlean-burnnaturalgasvehicles(NGVs).Pd/TiO2-Zr0.5Al0.5O1.75performsthebestcatalyticactivityamongthetestedfivecatalysts.ForCH4,thelight-offtemperature(T50)is254℃,andthecompleteconversiontemperature(T90)is280℃;forCO,T50is84℃,andT90was96℃.Varioustechniques,includingN2adsorption-desorption,X-raydiffraction(XRD),H2-temperature-programmedreduction(H2-TPR),X-rayphotoelectronspectroscopy(XPS),andscanningelectronmicroscopy(SEM)areemployedtocharacterizetheeffectofsupportsonthephysicochemicalpropertiesofpreparedcatalysts.N2adsorption-desorptionandSEMshowthatTiO2-Zr0.5Al0.5O1.75expressesuniformnano-particlesandlargemeso-porediametersof26nm.H2-TPRandXRDindicatethatPdOiswelldispersedonthesupportsandstronglyinteractedwitheachother.TheresultsofXPSshowthattheelectrondensityaroundPdOandtheproportionofactiveoxygenonTiO2-Zr0.5Al0.5O1.75aremaximaamongthefivesupports.

  • 标签: 天然气汽车 钯催化剂 CO氧化 稀薄燃烧 转化温度 PDO
  • 简介:以便调查设计方法因为一台微离心压缩机,它是一台极端微煤气汽轮机最重要部件,有2-dimensional片离心impeller二种类型被设计,生产并且测试。这些impellers与对方一起在南方飞机上有中心不同形状。而且,impeller这些类型为5被成为次和期末考试6次尺寸与4mm外部直径指向离心impeller以便为impellers估计类似。在impellers表演特征之中比较在表演和压缩机类似上揭示了南方配置影响。

  • 标签: 离心压缩机 超微型 配置 离心叶轮 原型 离心式压缩机
  • 简介:为为快速扫描激光横梁pulsing激光横梁和Galvano扫描仪Q开关被改编在水微滴操作微稳固粒子。由激光横梁照耀由一个钇铝柘榴石激光系统,导致流动,和粒子导致运动在微米大小直径套住好粒子被讨论。粒子旋转被使用各向异性微目标观察,并且而且旋转率与顺时针方向方向是22r/min。一只盖子杯子碎片在水微滴被混合,并且他们尺寸和形状是不平。没有由Galvano扫描仪扫描那个非范围旋转也在水里被观察。

  • 标签: 微小固体颗粒 诱发流动 操纵 激光辐射
  • 简介:ThispaperresentsanewX-rayimagingmethodswingLaminography(SL)thatissuitalbletoperformnon-destructivetestingontheslender-shapedmulti-layersamples.ComputersimulationsaremadetocomparethelimitedprojectionsinSLandtheprincipleofchoosingOptimalProjectionAngularRegion(OPAR)isdiscussed.Theexperimentonatwo-layerPrintedCircuitsBoardshowsthatSLwith120°swinganglesdistributedinOPARcangettheseparatedimagesofeachlayer.

  • 标签: 计算机图像处理 X射线图像处理 摇摆X射线分层法
  • 简介:Na0.5CoO2费密表面拓扑学用混合密度被学习功能理论。我们首先学习一个单身者(CoO2)(0.5-)有从0%~20%变化非局部Hartree-Fock交换百分比层模型。结果看那混合非局部Hartree-Fock交换是否仅仅在1%和5%之间,费密表面拓扑学类似于试验性。与在混合密度3%HF交换功能就在Na-0.5CoO2系统效果ofNa离子而言,我们结束费密表面被切开加倍洞,小差距在在Brillouin地区和费密表面之间交叉附近开。我们两个都,非局部Hartree-Fock数量在功能混合密度交换结果表演然后一离子在费密表面拓扑学上有许多影响。

  • 标签: 费米面 拓扑学 混合密度函数理论 分层模型 非局域性Hartree-Fock交换 Na0.5CoO2