简介:Poly(aryleneetherdiketone)swerepreparedbythearomaticnucleophilicdisplacementreactionof4,4’-difluorobenzilwithdifferentbisphenolsinthepresenceofan-hydrouspotassiumcarbonateindiphenylsulfoneatelevatedtemperature.Thepolymersobtainedhadinherentviscosityof0.51~0.63dL/g,andexhibitedglasstransitiontemper-aturerangingfrom136~217℃mainlydependingonthebisphenolsusedinthepolymersynthesis.Thermogravimetryofthesepolymersshowedexcellentthermalstability,indi-catingthat10%weightlossesofthepolymerswereobservedintherangeabove428℃and438℃inairandnitrogen,respectively.ThemechanicalpropertiesofthesepolymerswerealsodescribedandthepermeabilityoffivepolymersforH2,O2andN2wasdeterminedat30℃.
简介:Inthisarticle,westudytheexplicitexpressionsoftheconstantsintheerrorestimateofthenonconformingfiniteelementmethod.WeexplicitlyobtaintheapproximationerrorestimateandtheconsistencyerrorestimatefortheWilson'selementwithouttheregularassumption,respectively,whichimpliesthefinalfiniteelementerrorestimate.Suchexplicitapriorierrorestimatescanbeusedascomputableerrorbounds.
简介:1.IntroductionItiswellknownthattheAdini’selementiscommonlyusedforapproximatingthesolutionofhighorderpartialdifferentialequations(suchasplateproblem).WhatresultscanwegetifwesolvesecondorderimhomogeneousNeumannellipticproblemusingAdini’selement?Weshall...
简介:Energyandenvironmentalissueshavebecomeincreasinglyprominentinmattersoftransportation.Comparedwithroad,air,andseatransportation,railwaytransportationhastheadvantagesofalargetransmissioncapacity,withrapid,safe,andon-timetravel,requiringlesslandresources,withlowerenergyconsumption,lessenvironmentalpollution,andthecapacitytooperateundermostweatherconditions.Inparticular,high-speedrailwaytechnologyhasbeengrowingrapidly.Sincetheworld'sfirsthigh-speedrailwaywasbuiltinJapanin1964,morethantencountriesandregionshavedevelopedhigh-speedrailways,operatingoveratotalofmorethan10000km.High-speedrailwaysnotonlyprovidethepublicwithanewtypeofrapid,convenient,safe,andcomfortabletravel,butalsogreatlyboostthesocio-economicdevelopmentofthecountry.
简介:Liquid-solid(L-S)masstransfercoefficients(Ks)werecharacterizedinagas-liquid-solid(G-L-S)three-phasecountercurrentmagneticallystabilizedbed(MSB)usingamorphousalloySRNA-4asthesolidphase.Effectsofsuperficialliquidvelocity,superficialgasvelocity,magneticfieldstrength,liquidviscosityandsurfacetensionwereinvestigated.ExperimentalresultsindicatedthattheexternalmagneticfieldincreasedKsinthree-phaseMSB,ascomparedtothoseinconventionalG-L-Sfluidizedbeds;thatKsincreasedwithmagneticfieldstrength,superficialgasandliquidvelocitiesanddecreasedwithliquidviscosityandsurfacetension;andthatKsshoweduniformaxialandradialdistributionsexceptforsmallincreasesclosetothewall.DimensionlesscorrelationswereestablishedtoestimateKsoftheG-L-ScountercurrentMSBusingSRNA-4catalyst,withanaverageerrorof3.6%.
简介:Inthispaperwestudytheexistenceoflimitcycleforcubicsystem(E)3,ofKolmogorovtypewithaconicalgebraictrajectoryF2(x,y)=ax2+2bxy+cy2+dx+ey+f=0Ithasbeenprovedinmyformerpapersthat(E)3doesn’thaveanylimitcycleonthewholeplaneIfb2-ac≠0,Nowweareinvestigatingthecasewhereb2-ac=0.Weprovethesufficientandnecessaryformula(2)or(13)witbwhich(E)3musthaveaparabolictrajectoryF2(x,y)=0.Thentherewillnotbeanylimitcycleonthefullplane.Onthebasisofthis,weconclude:ThecubicsystemofKolmogorovtypewithanon-degeneratedquadraticalgebraictrajectoryonthewholeplanehasnolimitcycle.
简介:本文中,我们研究一类由极大Bochner—Riesz算子和Lipschtz函数A生成的多线性算子,获得了它的(Lp,上q)型,而且我们还将证明此算子从Lebesgue空间到Lipschtz空间、从Herz空间到Campanato空间和从Lp空间到Tribel—Lizorkin空间的有界性.
简介:Recently,Cristofaro-GardinerandHutchingsprovedthatthereexistatleasttwoclosedcharacteristicsoneverycompactstar-shapedhypersufaceinR~4.ThenGinzburg,Hein,Hryniewicz,andMacarinigavethisresultasecondproof.Inthispaper,wegiveitathirdproofbyusingindexiterationtheory,resonanceidentitiesofclosedcharacteristicsandaremarkabletheoremofGinzburgetal.
简介:AseriesofdoubleperovskitesRSrMnFeO_6(R=La,Pr,Nd,Sm)wassynthesizedundermildhydrothermalconditions.Crystalgrowthsofthesamplesweresensitivetoalkalinity,temperature,fillingfraction,andcompositionofinitialreactionmixture.ThedesiredseriesofcompoundsbelongstotheclassofAA'BB'O_6perovskiteswitharandomdistributionofMnandFeatomsovertheB-cationsub-lattice.TheirstructuresshowthedistortedorthorhombicsymmetrywithspacegroupPnma.TheshapesandsizesofthecrystalswereanalyzedonaRigakuJSM-6700Fbyscanningelectronmicroscopy.AnalysisdonebyXPS,MssbauerspectroscopyandiodometrictitrationrevealsthatMnandFeionshave+4and+3oxidationstates,respectively.
简介:.Thesingle2dilationorthogonalwaveletmultipliersinonedimensionalcaseandsingleA-dilation(whereAisanyexpansivematrixwithintegerentriesand|detA|=2)waveletmultipliersinhighdimensionalcasewerecompletelycharacterizedbytheWutamConsortium(1998)andZ.Y.Li,etal.(2010).Butthereexistnomoreresultsonorthogonalmultivariatewaveletmatrixmultiplierscorrespondingintegerexpansivedilationmatrixwiththeabsolutevalueofdeterminantnot2inL2(R2).Inthispaper,wechoose2I2=(2002)asthedilationmatrixandconsiderthe2I2-dilationorthogonalmultivariatewaveletY={y1,y2,y3},(whichiscalledadyadicbivariatewavelet)multipliers.Wecallthe3×3matrix-valuedfunctionA(s)=[fi,j(s)]3×3,wherefi,jaremeasurablefunctions,adyadicbivariatematrixFourierwaveletmultiplieriftheinverseFouriertransformofA(s)(cy1(s),cy2(s),cy3(s))?=(bg1(s),bg2(s),bg3(s))?isadyadicbivariatewaveletwhenever(y1,y2,y3)isanydyadicbivariatewavelet.Wegivesomeconditionsfordyadicmatrixbivariatewaveletmultipliers.TheresultsextendedthatofZ.Y.LiandX.L.Shi(2011).Asanapplication,weconstructsomeusefuldyadicbivariatewaveletsbyusingdyadicFouriermatrixwaveletmultipliersandusethemtoimagedenoising.