简介:Inthispaper,MPt/C(M=La,Nd)catalystsofPEMFCweresynthesizedbymicrowaveradiationprocess.ThecrystallinityandstructureofcatalystswererespectivelyanalyzedbyXRDandnitrogenadsorptiontests.Theactivityofcatalystswasinvestigatedbyelectrochemistryexperiment.Theresultsshowedthat:1)comparedwithPt/Ccatalystpreparedbytypicalimpregnation-reductionprocess,thesizeofMPt/CcatalystparticledecreasedandtheavailablecrystalforO2reductionincreased;2)theMPt/CcatalystshadrelativelyhighBETsurfaceareas;and3)thesecrystaltransformationsoftheMPt/Ccatalystbroughthightheelectrocatalyticactivity,andasaresult,improvedthepowerofPEMFC.
简介:Itiswellknownthateveryprimeidealminimaloveraz-idealisalsoaz-ideal.TheconverseisalsowellknowninC(X).ThuswheneverIisanidealinC(X),thenI~(1/2)isaz-idealifandonlyifIis,inwhichcaseI~(1/2)=I.Weshowthesamefactforz~o-idealsandthenitturnsoutthatthesumofaprimaryidealandaz-ideal(z~o-ideal)inC(X)whicharenotinachainisaprimez-ideal(z~o-ideal).Wealsoshowthateverydecomposablez-ideal(z~o-ideal)inC(X)istheintersectionofafinitenumberofprimez-ideals(z~o-ideal).Somecounter-examplesingeneralringsandsomecharacterizationsforthelargest(smallest)z-idealandz~o-idealcontainedin(containing)anidealaregiven.
简介:TheconstructionofadsorptivetypeC60modifiedelectrodeanditselectrochemicalreductionandoxidationbehaviorinaqueoussolutionsaredescribedinthisreport.Fourpairsofone-electrontransferreductionandoxidationcyclicvoltammetryisobtainedinaqueoussolutioncontaining30%CH3CNand2%(C2H5)4NOH.ItisreportedinthispaperthattheC60modifiedelectrodealsocatalyzestheelectrochemicalreductionofdissolvedoxygenin40%DMFand2%(C2H5)4NOHaqueoussolutionandthismightopenanewfieldforthepotentialapplicationsofC60inelectrochemistryandelectroaualyticalchemistry.
简介:Theapplicabilityandlimitationofseveralquadraticstrengththeorieswereinvestigatedwithrespectto2D-C/SiCand2.5D-C/SiCcomposites.Akindofdamage-basedfailurecriterion,referredtoasD-criterion,isproposedfornonlinearceramiccomposites.Meanwhile,thenewlydevelopedcriterionispreliminarilyvalidatedundertension-shearcombinedloadings.ThepredictionshowsthatthefailureenvelopegivenbyD-criterionislowerthanthatfromTsai–HillandHoffmancriteria.Thisrevealsthatthedamage-basedcriterionisreasonableforevaluationofdamage-dominatedfailurestrength.
简介:AnaturalcompactificationofthevirtualconfigurationspaceofNpointsontheRiemannsphereisconstructedbyusingcross-ratios.WeshowthatthiscompactificationishomeomorphictotheBers’compactificationofthevirtualmodulispaceofapuncturedRiemannsphereoftypeN.Inparticular,thesystemofglobalandexplicitcoordinatesofthisstandardcompactificationisgivenbycross-ratios.
简介:对[0,2π]年的区间I,对它的左右两个半区间L,R,定义一种加权原子形如b(t)=1/(p(t))[X1-XR(t)],其中ρ为满足某些性质的非负函数,加权原子b(t)的线性组合构成加权原子空间B(ρ),本文证明了如果f∈B(ρ),则f的Fourier级数的Cesaro平均几乎处处收敛。
简介:ThepaperdefinesanextendedCesàrooperatorTgwithholomorphicsymbolgintheunitballBofCnasWhereg(z)=∑j=1∑nzjg/zjistheradialderivativeofg.Inthispaper,theauthorcharacterizesgforwhichTgisbounded(orcompact)ontheBlochspaceBandthelittleBlochspaceB0.
简介:<正>LetXbeaconnectedfiniteCWcomplexanddx:KO(C(X))→Zbethedimensionfunction.Weshowthat,ifAisaunitalseparablesimplenuclearC*-algebraofTR(A)=0withtheuniquetracialstateandsatisfyingtheUCTsuchthatKO(A)=QkerdxandK1(A)=K1(C(X)).thenAisisomorphictoaninductivelimitofMn!(C(X)).
简介:由Ginchev在我们证明足够、必要的optimality条件的那一些的这篇文章获得了,Guerraggio,Luc[Appl。数学,51,5鈥?6(2006)]概括(严格地)那些由Guerraggio介绍了,Luc[J。Optim。理论Appl,109,615鈥?29(2001)]。当以前的纸显示出在那里给的条件是有效的为例子时但是从后者纸的失败,它不通常证明那它建议的条件更强壮。在现在的笔记,我们与缺乏的证明完成这比较。关键词C1,1功能-概括秒顺序方向性的衍生物-Dini衍生物-弱有效的minimizer-秒顺序先生(2000)题目分类49K10的孤立的minimizer-49J52-49J50-90C29-90C30由捷克的管理(MSM6198959214)的委员会支持了
简介:我们学习二维的non-self-similar的一个家庭的单个结构quasilinear的全球解决方案和他们的相互作用夸张能量守恒定律。当起始的断绝在仅仅上发生时,为盒子,二拆散统一圆和起始的数据是二个不同经常的状态,全球答案被构造,一些新现象被发现。在分析,我们首先为0t构造答案
简介:At-hyperwheel(t≥3)oflengthl(orW(t)lforbrevity)isat-uniformhypergraph(V,E),whereE={e1,e2,...,el}andv1,v2,...,vlaredistinctverticesofV=∪eii=1lsuchthatfori=1,...,l,vi,vi+1∈eiandei∩ej=P,j∈/{i1,i,i+1},wheretheoperationonthesubscriptsismodulolandPisavertexofVwhichisdifferentfromvi,1≤i≤l.Inthispaper,theminimumcoveringproblemofMCλ(3,W(3)4,v)isinvestigated.DirectandrecursiveconstructionsonMCλ(3,W(3)4,v)arepresented.Thecoveringnumbercλ(3,W(3)4,v)isfinallydeterminedforanypositiveintegersv≥5andλ.
简介:采用密度泛函方法对11顶点巢式碳硼烷C2B9H112-异构体进行了几何结构优化,分析了稳定性、电荷分布及分子轨道.结果表明,9个异构体都有对应的稳定构型,保持了巢式骨架结构.C取代开口五元环上B的异构体更稳定,且随取代数目增加和C原子间距增加而增加,C—C键和C—B键作用增强.C取代内层B使异构体稳定性降低,C—C键和C—B键长随之增长.负电荷主要集中在C原子上,开口五元环上的C原子上负电荷要比内层C原子更多,成为亲核取代反应中心.异构体分子前线轨道具有和η5-C5H5-相似的π键性质,ΔELUMO-HOMO反映的化学稳定性与结构能量稳定性趋势一致.
简介:牛顿的重复为单个Toeplitz矩阵的组逆的计算被修改。在每次重复,重复矩阵被一个矩阵与一个低排水量等级接近。因为重复矩阵的排水量结构,涉及牛顿的重复的thematrix向量增加能高效地被做。我们证明修改牛顿重复的集中仍然是很快的。数字结果被介绍表明建议方法的快集中。