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简介：Non-lineardevelopmentofdoubletearingmodesinducedbyelectronviscosityisnumericallysimulated.MHDflowlayersaredemonstratedtomergeinthedevelopmentofthemodes.Theshearedflowsareshowntoliejustattheboundariesofthemagneticislands,andtohavesuffcientlevelsrequiredforinternaltransportbarrier(ITB)formation.PossiblecorrelationbetweenthelayerformationandtriggeringofexperimentallyobservedITBs,preferentiallyformedinproximitiesofrationalfluxsurfacesoflowsafetyfactors,isdiscussed.

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简介：AdustsedimentlayerwasfoundontheoutertubewallwhentheESCP(electrostaticcentrifugalprecipitator)trappeddieselparticulatesorganistersand.TheComptonbackscattermethodwasusedtomeasurethesedimentthicknessduringtheexperiment.Theeffectoftheinletgasvelocityonthedustsedimentlayerwasinvestigated.PIV(ParticleImageVelocimetry)wasusedtomeasurethevelocityfieldbetweentheinnerbarbtubewallandtheoutertubewall.Experimentsshowedthatthethicknessofthesedimentincreasedwithtime,andthesedimentlayeratthelowerendwasmuchthickerthanthatattheupperend.Theagglomerationontheoutertubewallcouldberemovedwhentheinletgasvelocitywasincreasedtoacertainvalue.

简介：Synchrontronradiationx-rayreflectivitymeasurementisusedtostudytheconcentrationprofileofaδ-dopedErlayerinSiepitaxialfilmgrownbymolecular-beamepitaxy.Theoscillationofthereflectivityamplitudeasafunctionofreflectionangleisobservedintheexperiment.Bydoingatheoreticalsimulation.theconcentrationprofileofEratomscouldbederied.Itisshownthattheoriginallygrownδ-dopedErlayerchangesintoanexpionentiallydecayedfunctionduetotheErsegregation.Thetemperaturedependenceofthe1/edecaylengthindicatesthatthesegregationisakineticallylimitedprocess.Theactivationenergyisdeterminedtobe0.044±0.005eV.

简介：Itisaverydifficulttasktodevelopamethodofreducingturbulentboundarylayerdrag.However,inrecentyears,plasmaflowcontroltechnologyhasdemonstratedhugepotentialinfrictiondragreduction.Tofurtherinvestigatethisissue,asmoothplatemodelwasdesignedasatestingobjectarrangedwithabidirectionaldielectric-barrier-discharge(DBD)plasmaactuator.Inaddition,measurementofskinfrictiondragwasachievedbyapplyinghotwireanemometrytoobtainthevelocitydistributionoftheturbulentboundarylayer.AmethodofquantifyingthefrictiondrageffectwasadoptedbasedontheSpaldingformulafittedwiththeexperimentdata.Whenplasmaactuationwasconducted,avelocitydefectoccurredatthetwomeasuringpositions,comparedwiththenoplasmacontrolcondition;thismeansthattheDBDplasmaactuationcouldreducethedragsuccessfullyinthedownstreamoftheactuator.Moreover,dragreductioncausedbybackwardactuationwasslightlymoreefficientthanthatcausedbyforwardactuation.Withanincreasingdistancefromplasmaactuation,thedrag-reductioneffectcouldbecomeweaker.Experimentalresultsalsoshowthattheimprovementofdrag-reductionefficiencyusingaDBDplasmaactuatorcanachieveabout8.78%inthelocalregionoftheexperimentalflatmodel.

简介：Magneticspectrumoftheelectromagneticioncyclotronwavesintheterrestrialplasmadepletionlayer（PDL）aresometimesobservedtohaveaBIF（bifurcated）signature,whereadiminutionaround0.5ΩpwithΩptheprotongyrofrequency,occursbetweentwoactivitypeaksinthespectrum.Byone-dimensionalhybridsimulations,theeffectofrelativedriftvelocitiesbetweenprotonsandHe2+onthemagneticspectralsignaturesinthePDLisstudied.Theresultsshowthattherelativedriftvelocityenhancesthedevelopmentofprotoncyclotronwavesanddeclinesthedevelopmentofheliumcyclotronwaves.Theprotoncyclotronwavesarefirstlyexcited,andfollowedbytheexcitationofheliumcyclotronwavesduetotheincreaseintherelativedriftvelocity.Moreover,theboundarybetweentwoactivitypeaksgetsobscure.

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简介：Interactionbetweenhigh-intensitypulsedionbeam(HIPIB)andadouble-layertargetwithtitaniumfilmontopofaluminumsubstratewassimulated.Thetwo-dimensionalnonlinearthermalconductionequations,withthedepositedenergyinthetargettakenassourceterm,werederivedandsolvedbyfinitedifferentialmethod.Asaresult,thetwo-dimensionalspatialandtemporalevolutionprofilesoftemperaturewereobtainedforatitanium/aluminumdouble-layertargetirradiatedbyapulseofHIPIB.Theeffectsofionbeamcurrentdensityonthephasestateofthetargetmaterialsnearthefilmandsubstrateinterfacewereanalyzed.BothtitaniumandaluminumweremeltedneartheinterfaceaRerashotwhentheionbeamcurrentdensityfellintherangeof100A/cm~2to200A/cm~2.

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简介：通过水热法合成了骨架含铁的杂原子丝光沸石，采用XRD，FT－IR及TPR等表征技术确认铁进入了分子筛骨架。利用XAFS技术对分子筛中铁的精细结构和配位环境进行了表征和计算，近边吸收的Fe-K边前跃迁证实铁在分子筛骨架中位于四面体配位环境中，与邻近原子存在共价键作用；铁－氧配位键长为0.188-0.189nm.

简介：利用Triton和高盐处理制备菠菜光合系统ⅠⅠ（PSⅠⅠ）－La复合物，并应用EXAFS技术研究了该复合物中稀土镧的局域结构。初步结果表明，镧与PSⅠⅠ中O或N原子配位，配位数为8，距离为2．5A左右；第二层配位原子是C，其作用距离为3．5A左右，配位数为4；La与Mn的作用距离4．5A，大于Ca与Mn的距离3．5A。由此推测镧与PSⅠⅠ结合后，改变了其空间结构。

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简介：应用同步辐照光源进行高温高压原位能量色散X射线衍射实验，入射X射线光束定位是关键，北京同步辐射实验室高压衍射站引入四刀光阑扫描系统，实现调光定位自动化，简化调光手续，提高实验效率，为高压衍射实验站的用户进行实验提供了方便。

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简介：用溶胶－凝胶方法合成了掺铒（掺杂浓度10^20/cm^3)的二氧化硅玻璃。在室温下可产生1.54μm波长的红外荧光。实验结果表明：荧光强度随掺杂浓度的不同而改变，并在0.5W%的掺杂浓度下出现最大值。当温度从4K升至300K时，荧光强度下降了74％。通过FT－IR和EXAFS检测，Er离子与O组成了配位数为8或9的配位结构。

简介：利用同步辐射X光衍射技术，对（La1-xBix)0.5Ca0.5MnO3(x=0.2,0.3,0.4）中存在的Jahn-Teller畸变，进行了原位的高压研究。实验表明在外加压力的作用下，能有效地影响到晶格中Mn-O键长和Mn-O-Mn键角的变化，样品中的晶格畸变有所减小。并且对在晶格中存在的两种不同的畸变模式Q2和Q3，在外加压力的作用下的变化规律进行了讨论。由于这两种不同的畸变模式在受到外力作用时，表现形为不一样，导致了位于a-b基面上的Q2畸变模式的消失，并且导致Q2畸变模式消失的压力点随掺杂浓度的增加而增加。

简介：小角X射线散射（SAXS）是一种有效的、重要的亚微结构分析手段。本文介绍了SAXS的基本原理、实验方法和数据处理方法尤其是对于非理想两相体系的解析方法及其在溶胶－凝胶法制备多孔材料研究中的应用。

简介：实验观测到X射线反向曲线具有双晶特征。研究表明缺陷聚集在孪晶晶界。应力在晶界边缘处得到释放。应力的释放导致享晶和其它缺陷的形成。由于缺陷的形成在缺陷的附近产生无位错无应力或低位错小应力区。因此我们提出一种孪晶模型来解释实验结果。应力（主要是热应力），化学配比的偏离和杂质的非均匀分布是液封直接（LEC）InP单晶生长过程中产生孪晶的主要因素。研究了液封直拉（LEC）InP(111）面上的孪晶。本文中讨论了上面提到的孪晶模型的实验证据和如何得到无孪晶液封直接（LEC）InP单晶。