简介:在这篇文章,在三维的Lorentz空间的类似的运动的性质被调查。另外,在速度之间的一些几何结果和在一个空间运动的一个点的加速向量被获得。给词调音:类似的运动;空间kinematics;Lorentzian几何学
简介:引入强3-Armendafiz环的概念,研究了它们的性质。给出环R是强3-Armendariz环的充要条件。构造了是强3-Armendariz环但不是幂级数Armendariz环的例子。证明了若环R是约化环,则R[x]/(xn)是强3-Armendariz环,其中(xn)是由xn生成的R[x]的理想。
简介:这篇论文的目的是在3-dimensional上在equivariant操作之中学习关系小的封面。作者为这些操作得到三个公式。作为应用,在面向的3-dimensional的构造的Nishimura鈥檚定理在所有3-dimensional的构造的小封面和L眉-于鈥檚定理小封面被改进。而且为3-dimensional2花托manifolds的构造,它被看那,所有操作能被使用equivariant手术获得。关键词Equivariant外科-有限的组行动-小盖子-3-dimensional歧管-3-dimensional简单polytope2000苏布杰克特先生分类57M50-57M60-57S17-52B10工程由复旦大学支持了,通过朝鲜(NRF)的国家研究基金会的Fujyukai基金会和基本科学研究节目由教育部资助了,科技(号码2009-0063179)。
简介:TheencapsulationofstearicacidcoatednanometerCaCO3byapolystyrene(PS)networkviaemulsionpolymerizationisdescribed,whereγ-methacryloxypropyltrimethoxysilane(MPS)wasusedasanefficientcrosslinker.TheimportantfactorssuchasthetypeandamountofsurfactantandinitiatorandthecontentofCaCO3areinvestigatedaswellastheroleofMPS.IthasbeenshownthatlittlePSwasextractablewithonly0.6wt%ofMPS(relativetostyrene).Thecationicsurfactantcetyltrimethylammoniumbromide(CTAB)provedmoreeffectivethantheanionicsurfactantsodiumdodecylsulfonate(SDS).Theyieldrises,particlesbecomesmallerandsizedistributionbroadenswithincreasedamountofCTAB.Itisalsofoundthateither2,2′-azobis(isobutyronitrile)(AIBN)orammoniumpersulfate(APS)issuitableforattaininghighmonomerconversion.WithincreasedamountofCaCO3,theencapsulationratiocanbevariedfrom17.9to3.6,whilemonomerconversionandyielddecreaseslightly.FT-IRspectraoftheproductsafterextractionindicatetightencapsulationbetweenPSandCaCO3,andTEMphotographsofcompositeparticleswithwell-definedcore-shellstructuregivedirectevidenceofencapsulation.
简介:Layereddoublehydroxides(LDHs)withhydrotalcite-typestructurecontainingFe3+,Al3+andMg2+werepreparedbymeansofacoprecipitationmethod.Theproductswerecharacterizedbyelementanalysis,X-raypowderdiffractionandtransmissionelectronmicroscopy.Itwasfoundthatevenifthemolarratioofn(Fe+Al)/n(Fe+Al+Mg)>0.33,yetapurehydrotalcite-likecompound(HTlc)phasewasgainedwhenn(Fe)/n(Al+Mg+Fe)≤0.30andn(Al)/n(Al+Mg+Fe)≤0.30;theAl(OH)3phaseappearedintheproductswhenn(Al)/n(Al+Mg+Fe)>0.30;andanamorphousphaseemergedwhenn(Fe)/n(Al+Mg+Fe)>0.33.TheseresultsshowthatthereisnoconcentrationsuperpositioneffectbetweenFe3+andAl3+onthecrystallinestateoftheproducedsamples.Inourpreviouswork,theconcentrationsuperpositioneffectbetweenZn2+andMg2+inthesynthesisofZn-Mg-Al-LDHswasfound.ForthepreparedFe-Al-Mg-LDHssamples,thevalueoflatticeparameteraisbetween0.30-0.32nm;andthevalueoflatticeparametercisbetween2.30-2.47nm,thebasalspacingisintherangeof0.76-0.83nm.Whentheratioofn(Fe)/n(Al)isaconstant,thevaluesofaandcincreasewiththeincreaseoftheMg2+contentoftheproducedsamples.Themeanparticlesizeandthemeancrystalgrainweredeterminedbyvirtueofaparticle-sizeinstrument,XRD-ScherrerformulaandTEMmethod,respectively.
简介:WepresentthetemperaturedependentelectricaltransportmeasurementsofAg/Si(111)-(√3×√3)R30°bytheinsitumicro-four-pointprobemethodintegratedwithscanningtunnelingmicroscopy.Thesurfacestructurecharacterizationsshowhexagonalpatternsatroomtemperature,whichsupportstheinequivalenttriangle(IET)model.Ametal-insulatortransitionoccursat-115K.Thelowtemperaturetransportmeasurementsclearlyrevealthestronglocalizationcharacteristicsoftheinsulatingphase.
简介:LargeGdCa4O(BO3)3crystalhasbeengrownbytheCzochralskimethod.ThequalityofGdCa4(BO3)3crystalwasassessedbywhite-beamsynchrotronradiationtopography.Ithasbeenfoundthatthereisasub-grainboundaryintheGdCa4O(BO3)3crystal.TheboundarydividesthelargeGdCa4O(BO3)3crystalintotwoindividuals.Duetothemisorientationbetweenthetwoindividuals,theimageshiftscanbeobservedinthesynchrotrontopopraphs.BasedonthemisorientationdeterminedbyhighresolutionX-raydiffractometer,theimageshiftswerecalculatedforseveralreflections.ThecalculationsareinagreementwiththemeasurementsfromthetopogrphsveryWell.Inaddition,theformationmechanismofsub-grainboundaryisdiscussed.2001ElsevierscienceB.V.Allrightsreserved.
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简介:采用密度泛函B3LYP/6-311G(d,p)方法对CH3F与C2H3的反应体系进行了理论研究,获得了反应的势能面信息及可能的微观机理.在QCISD(T)/6-311++G(d,p)水平上精确计算了各反应物种的单点能.结果表明,除抽提氢反应外,标题反应还存在抽提氟(R1)、消氟化氢(R2)、消氢(R3)和自由基形成(R4)四类反应.在QCISD(T)/6-311++G(d,p)//B3LYP/6-311G(d,p)水平上,R1,R2,R3和R4反应的能垒分别是163.9,152.2,209.8和224.2kJ·mol-1,相应反应能为-56.6,-164.3,-2.7和-156.0kJ·mol-1,所有反应均放热,为热力学允许的反应.
简介:The1,1'-binaphtholbasedoligomers3and7with3,3'-acetylene-phenylene-acetylenespacerwerepreparedfromBINOL1.ThehighopticalrotationvalueandCDspectrademonstratedthemainchainchiralityoftheoligomermolecule.TheUV-VISandfluorescentspectraevidencethecharacteristicsofconjugatedstructure.Incomparisonwitholigomer2bearing3,3'-acetylenespacer,theoligomers3and7havelongerefficientconjugationsegment,andtheirfluorescentquantumyields(φ)increased(0.60-0.65versus0.14).Extendingtheeffectiveconjugationsegmentwouldimprovethephotophysicalpropertiesofchiralconjugatedpolymers.``
简介:FiveC3/C3fluoroquinolonedimerstetheredwithafusedheterocyclicringofs-triazolo[2,1-b][1,3,4]thiadiazolederivedfromantibacterialquinolonesweresynthesizedandcharacterized,andtheirinvitroantitumoractivityagainstL1210,CHOcelllineswasevaluatedviatherespectiveIC50values.
简介:在多孔的媒介和液体之间的热和集体转移是一个复杂联合过程,它广泛地在设计应用的各种各样的地里被使用,特别为在油和煤气的抽取的自然、人工的破裂。在这研究,一个新方法被建议在破裂处理流动和稳定的流动的热转移问题。在破裂的液体流动用象Mohais的一样的方法被描述,与多孔的墙,和不安方法把破裂看作了一条隧道的人,被用来解决数学模型。不同于以前的研究,shear跳Ochoa-Tapia和Whitaker建议的边界状况在在液体和多孔的媒介之间的接口被使用。主要方法是不安分析和申请砍跳边界条件。渗透的影响,隧道宽度,砍跳在隧道的流动和热转移上的度和有效动态粘性被分析分析答案学习。在有典型参数和热转移的敏感的变化的隧道的轴的速度的分发被获得。
简介:Inthispaper,least-squaxesmirrorsymmetricsolutionformatrixequations(AX=B,XC=D)anditsoptimalapproximationisconsidered.Withspecialexpressionofmirrorsymmetricmatrices,ageneralrepresentationofsolutionfortheleast-squaresproblemisobtained.Inaddition,theoptimalapproximatesolutionandsomealgorithmstoobtaintheoptimalapproximationareprovided.
简介:Regardforthefuzzinessandtherandomnessinsomeacousticfields,amethodforthenumericalanalysisofthe2DacousticfieldwithFuzzy-Randomparameterswasproposedbasedontheequivalentconversionofinformationentropy.Intheproposedmethod,afuzzyrandomacousticfieldwastreatedasapurefuzzyacousticfieldorapurerandomacousticfieldbytransformingallthevariablesintofuzzyvariablesorrandomvariables.Perturbationfiniteelementmethodsforanalyzingthetwo-dimensionalacousticfuzzyandrandomfieldarededuced.Thesoundpressureresponseofa2Dacoustictubeandthe2Dacousticcavityofacarwithfuzzy-randomparameterswereanalyzedbytheproposedmethodandtheMonteCarlomethod,theresultsshowthattheproposedmethodcanbewellappliedtothenumericalanalysisofthe2Dacousticfieldwithfuzzy-randomparameters,andhasgoodprospectofengineeringapplication.
简介:Laminatedcompositematerialsarewidelyimplementedinseveralengineeringconstructions.Foritsrelativelightweight,thesematerialsaresuitableforaerospace,military,marine,andautomotivestructuralapplications.Toobtainsafeandeconomicalstructures,themodellinganalysisaccuracyishighlyrelevant.Sincemeshlessmethodsintherecentyearsachievedaremarkableprogressincomputationalmechanics,thepresentworkusesoneofthemostflexibleandstableinterpolationmeshlesstechniqueavailableintheliterature—theRadialPointInterpolationMethod(RPIM).Here,a2Dapproachisconsideredtonumericallyanalysecompositelaminatedbeams.Boththemeshlessformulationandtheequilibriumequationsrulingthestudiedphysicalphenomenonarepresentedwithdetail.Severalbenchmarkbeamexamplesarestudiedandtheresultsarecomparedwithexactsolutionsavailableintheliteratureandtheresultsobtainedfromacommercialfiniteelementsoftware.Theresultsshowtheefficiencyandaccuracyoftheproposednumerictechnique.