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简介：BSTOdielectricceramicwaspreparedfromSrTiO3andBaTiO3powderssynthesizedbyhydrothermalmethod,aswellasfromBa0.6Sr0.4TiO3powdersynthesizedbyconventionalsolid-statereaction.Theformercanbesinteredatarelativelylowtemperatureof1120℃.CharacterizationbySEMshowedthatthegrainshapesofbothceramicsarecubical,thoughthegrainsizeoftheformerismuchsmaller.Dielectricconstantsmeasuredat20℃wereshowntovarywithfrequencyintherangefrom1kHzto2MHzanddcbiasfield,andfurtherthatthedielectriclossoftheformertobelessthan2×10-3inthefrequencyrangeof20kHzto1MHz,muchsmallerthanthatofthelattersample.Fortheformer,temperaturedependenceofdielectricconstantismuchflatterandthereexistsanextendedphasetransitiondiffusioncoveringawidetemperaturerangeofCurietemperatureTc.Thesmallergrainsizeoftheformerdepressesthedcbiaselectricalfielddependenceofdielectricconstant.Thetunabilityis7%underabiasfieldof0.6kV/mmdc.

简介：TiO2@ZrO2@Y2O3:有coremultishell结构的Eu3+合成粒子通过layer-by-layer(LBL)的联合被综合自己组装方法和一个solgel过程。获得的样品与扫描电子被描绘显微镜学(SEM)，传播电子显微镜学(TEM)，X光检查光电子光谱学(XPS)，X光检查衍射(XRD)，和荧光spectrophotometry。结果证明合成粒子有coremultishell结构，球形的形态学，和狭窄的尺寸分布。TiO2核心上的ZrO2层的存在能有效地阻止在TiO2核心和Y2O3壳之间的反应；为在在TiO2@ZrO2@Y2O3的TiO2核心和Y2O3壳之间的反应的温度:Eucoremultishell黄磷能被300提高

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简介：3阶段的水动力学反的使流体化的床为不同液体和煤气的速度用低密度粒子试验性地被学习。水动力学特征学习了包括压力落下，最小的液体和气体使液化速度和阶段劫盗。用床压力坡度决定的最小的液体使液化速度，随气体的增加减少速度。液体劫盗沿着床高度增加的阶段劫盗表演的轴的侧面，而稳固的劫盗减少，击倒床。然而，煤气的劫盗在床上是几乎一致的。

简介：A3-DnonlinearproblemofsupercavitatingflowpastanaxisymmetricbodyatasmallangleofattackisinvestigatedbymeansoftheperturbationmethodandFourier-cosine-expansionmethod.Thefirstthreeorderperturbationequationsarederivedindetailandsolvednumericallyusingtheboundaryintegralequationmethodanditerativetechniques.Computationalresultsofthehydrodynamiccharacteristicsandcavityshapesofeachorderarepresentedfornonaxisymmetricsupercavitatingflowpastconeswithvariousapex-anglesatdiffer-entcavitationnumbers.Thenumericalresultsarefoundingoodagreementwithexperimentaldata.

简介：Soilconsolidationwouldinducevariationsofitstransportcoefficientssuchashydraulicconductivityanddiffusioncoefficient.Thispaperpresentsastudyoftheinfluenceofbarrierconsolidationontransportcoefficients,anda3Dtransportmodelbasedonmixturetheoryisproposedfordescribingthelinersthatinvolvecirculardefectsinthegeomembrane.TheelastoplasticALPHAmodelisrevisedbyusingthespatiallymobilizedplane(SMP)criterionforsimulatingthedeformationofthesoils.Then,the3Dmodelcouplingthenonlinearconsolidationandcontaminantadvection-diffusionissolvedusingthefiniteelementsoftwareABAQUS.Theresultsshowthattheimportanceofreducingthedefectsizeinthegeomembraneandthelinerporositytocontrolthecontaminantconcentrationincrease.

简介：TheIsodynetechniquebasedonthescatteredlightscanningfromathinlaserbeamcanbeusedtoobtaintheinformationinsidetheloadedobjectintheroomtemperaturenondestructively,soitisaverypowerfultechniquein3Dstressanalysis.Theproblemsarehowtointerprettheinformationandhowtogetsufficientinformationfromthefewinterferencefringe.Birefringencephaseshifttechniquecandistinguishthefringeordersautomaticallyandenrichtheinformationin256graylevelsbetweenmaximandminimlightintensity.InthepapertheIsodynebirefringencephaseshiftmethodwithanobliqueincidenceandequilibriumequationispresented,bywhichthe3DstressesinthemiddleplaneofaplatewithUshapenotchareseparatedsuccessfully.

简介：Basedonthegeneralconservationlawsincontinuummechanics,theEulerianandLagrangiandescriptionsofthejumpconditionsofshockwavesin3-dimensionalsolidswerepresentedrespectively.Theimplicationofthejumpconditionsandtheirrelationsbetweeneachother,particularlytherelationbetweenthemassconservationandthedisplacementcontinuity,werediscussed.Meanwhiletheshockwaveresponsecurvesin3-dimensionalsolids,i.e.theHugoniotcurveswereanalysed,whichprovidethefoundationforstudyingthecouplingeffectsofshockwavesin3-dimensionalsolids.

简介：The1/3subharmonicsolutionfortheDuffing'sequationisinvestigatedbyusingthemethodsofharmonicbalanceandnumericalintegration.Thesensitivityofparametervariationforthetransientprocessandthetransientprocessfortheperturbanceinitialconditionsarestudied.Overandabove,theprecisionofnumericalintegrationmethodisdiscussedandthenumericalintegrationmethodiscomparedwiththeharmonicbalancemethod.Finally,asymptoticalstabilityofthepuresubharmonicoscillationselementisinspected.

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.

简介：Becausemostpiezoelectricdeviceshaveinterfaceswithfluidinengineering,itisvaluabletostudythecoupledfieldbetweenfluidandpiezoelectricmedia.Asthefundamentalproblem,the3DGreen'sfunctionsforpointforcesandpointchargeloadedinthefluidandpiezoelectricbimaterialsarestudiedinthispaper.Basedonthe3Dgeneralsolutionsexpressedbyharmonicfunctions,weconstructedthesuitableharmonicfunctionswithundeterminedconstantsatfirst.Then,thecouplefieldinthefluidandpiezoelectricbimaterialscanbederivedbysubstitutionofharmonicfunctionsintogeneralsolutions.Theseconstantscanbeobtainedbyvirtueofthecompatibility,boundary,andequilibriumconditions.Atlast,thecharacteristicsoftheelectromechanicalcoupledfieldsareshownbynumericalresults.

简介：为了最大限度克服微机电陀螺的两个模态的相互耦合作用,提高微机电陀螺的综合性能指标,采用国内现有MEMS标准工艺方法,设计和制作了一种高性能单晶硅对称解耦结构的线振动陀螺。采用对称结构形式和保证陀螺驱动和检测模态振型都是弯曲振动模式,易于模态匹配;由于采用驱动模态和检测模态结构解耦方式,从微结构设计上大大降低了正交耦合误差影响,使陀螺具有输出零位小、零偏稳定性好的优点。测试结果表明：初次加工的样机,在大气中驱动和检测模态固有频率分别在2430Hz和2580Hz左右,在150Hz带宽内具有0.1～0.5（°）/s的分辨率;随着加工精度的提高和检测电路的改进,该陀螺在大气中15Hz带宽内实现0.008（°）/s的分辨率,在真空状态下,这种高性能单晶硅对称解耦结构的线振动陀螺性能会有进一步的提高。

简介：Thisletterobtainsatyphoon-likevortexsolutionbysolvingtheBragg-Hawthorneequation.ThesolutiondescribesspiralpathsoffluidmaterialelementontheBernoullisurface,whereassomenewexactsolutionsareobtainedwhichareboundedinthewholeregion.Thefirstoneisacontinuedumbrellavortexsolution,whichisatyphoon-likevortex.Thesecondoneisamulti-planarsolution,whichisperiodicinz-coordinate.Withineachlayer,thereisanumbrellavortexsolutionsimilartothefirstone.Theabove...

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简介：ThisstudypresentsanovelprocessofinsitusurfacemodificationofCaCChnanoparticlesusingamultipleorificedispersionmicroreactor.CO2/Ca（OH）2precipitationreactionwasemployedtoprepareCaCO3nanoparticleswithsodiumstearatesurfactant.SynthesizedCaCChproductswerecharacterizedbythermogravimetricanalysis（TGA）,infra-red（IR）,X-raydiffraction（XRD）,transmissionelectronmicroscopy（TEM）andBrunauer-Emmet-Telleranalysis（BET）.Theeffectofvariousoperationparametersonnanoparticlesandthedosageofsodiumstearateweredetermined.Theresultsshowedthatthepreparationprocesscouldbepreciselycontrolledwithefficientmasstransferprocess.Theparticleswerehighlyhydrophobicwithacontactangleof117andmonodispersewithanaveragesizeof30nm.Theadsorptionsofsodiumstearateandcalciumiononsolidparticlesduringtheinsitusurfacemodificationprocesswereinvestigated.

简介：准确地给出激波位置信息对于激波装配极为重要.但是,在使用计算流体力学（computationalfluiddynamics,CFD）方法模拟复杂流动时很难准确地给出激波的位置.根据激波捕捉得到的流场信息确定的激波位置往往带有极大误差,在定常问题的模拟中,这种误差可以随着迭代逐渐消除,然而在非定常问题的模拟中,这种误差往往会积累甚至导致计算崩溃.文章将基于特征线理论的激波辨识技术应用到激波装配中,根据已有流场信息准确判断激波的位置.对于定常问题,该方法的应用加速了收敛速度;对于非定常问题,该方法的应用可以极大地避免初始误差的产生.

简介：推导了线振动微机械陀螺的三自由度误差力学方程，并详细分析了陀螺耦合误差的产生机理。分析结果表明，各种结构误差是导致陀螺耦合误差信号的主要原因。在此基础上，利用振动和模态理论给出了陀螺结构误差参数的分离和辨识的试验方法和结果。试验结果表明，同相耦合分量和正交耦合分量是微机械陀螺的两种主要误差信号，造成正交耦合的主要原因是驱动轴和检测轴之间的刚度耦合以及驱动轴和检测轴各自的刚度不对称，造成同相耦合的主要原因是驱动轴和检测轴之间的阻尼耦合以及检测轴刚度不对称和驱动力不对称。结构误差参数的分离和辨识试验方法将为下一步的陀螺结构优化、微加工工艺改进以及耦合误差抑制提供基础。

简介：AnovelmethodformodelingcellularmaterialsisproposedbasedonMATLABimageprocessingandsynchrotronX-raycomputedtomographyscanningtoobtainanaccuratecalculationresultofaluminumfoambasedonfiniteelementmodel.Themaximumentropyalgorithmisemployedtoobtainthebinarizationimage,andthemedianfilteringalgorithmisusedtoreducethenoiseafterbinarization.Theexternalcontourandinternalporesboundaryisextractedbythe"edge"functioninMATLAB,andthegeometricalmodelisreconstructed.Atwo-stepmeshalgorithmisadoptedtomeshthereconstructedgeometricalmodel.Accordingly,thefiniteelementmodelofaluminumfoamisestablishedbytheproposedmethodbasedonreconstructiongeometricalmodel.Thecompressionbehaviorofaluminumfoamisobtainedat25℃,100℃,200℃byABAQUS,andgoodagreementswithexperimentsareachievedbyapplyingthepresentreconstructionalgorithmandmodelingmethod.

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