On the Oscillation of the Fourth Order Differential Equations

61.IntroductionWeconsiderthefourthorderdifferentialequationx(`)(t)-p(t)lx(t)I'sgnx(t)=O,(1.l)wherea>l,isconstant,andp(t)ispositivecontinuousfunctionon[t,,oo),to>o.Werestrictourattentiontothosenontrivialsolutionsx(t)of(1.1)whichexistonsomehalf-[ine[T:,co)cy[t,,oo),suchasolutioniscalledapropersolutionof(1.l).ApropersolutioniscalledoscillatoryifithasarbitrarilylargezerosFotherwiseitiscallednonoscillatory.Wecon-sidertheoscillationandnonoscillationofpropersolutionsof(l,l).WeletEdenotethesetofall…     

LONG TIME ASYMPTOTIC BEHAVIOR OF SOLUTION OF DIFFERENCE SCHEME FOR A SEMILINEAR PARABOLIC EQUATION (Ⅱ)

1.IntroductionLetfi~(0,l),f(x)EH'(fl),"o(x)EH'(fl)nHI(fl),of(u)=u3,weconsiderthefollowinginitial-boundaryvalue'problem:Bytheusualapproach[1--4]wecangettheglobalexistenceofthesolutionof(1.1),furthermore,thesolutionof(1.1)convergestothesolutionofthefollowingstationaryproblem(1.2)ast-co.l)TheProjectissupportedbyChillaPostdoctoralScienceFoundationandtheScienceFoundationofAcademyofEngineeringPhysicsofChinaIn[6]5[7]?theauthorsconsideredtheexplicitschemefor(l.l)asf(x)=0andonlytheestimateinLZf…     

关于Heisenberg流形Weyl律的余项(Ⅱ)

研究(2l 1)维无理Heisenberg流形上Weyl律余项的平方积分均值,并得到了渐近公式.     

Oscillation of Neutral Equations withVariable Coefficients

51iIntroductionConsidertheneutralequationwithvariablecoefficientsInrecentyears,thedscillatotytheoryforneutralequathaiswelldeveloped.Inparticular,manydifferentsuffitientconditionsfortheoscillationofallsolutionsofEq.(l)areobtainedin[l-7j.Allthepapersmentionedexcept[6],however,alwaysassumeP(t)isinoneofthefOllowingranges:OSP(t)SlorP(t)2l.Ouraiminthispapertoeatablishnewsufficientcon-ditionsfortheoscillationofallsolutiOnsofEq.(l)underlessrestrictivehypothesesonP(t).Letm=max{Y,d}.Byasolutionof…     

POSITIVE SOLUTIONS OF FOURTH-ORDER TWO-POINT BOUNDARY VALUE PROBLEMS

1IntroductionInthispaper,weconsidertheexistenceofpositivesolutionsoftheequationwithoneofthefollowingsetsofboundaryvalueconditionsWhenthefunctionf(x,y)p)inequation(l.1)isoftheformf(x,y,p)Hy,theboundaryvalueproblem(l.1)-(1.2)describesthedeformationsofanelasticbeambothofwhoseendssimplysupportedat0and1,andtheboundaryvalueproblem(1.l)-(l.3)describesanelasticbeamwithoneofitsendsimplysupportedandtheotherendclampedbyslidingclamps.In[11,Aftabizadehshowedtheexistenceofasolutionto(l.l)-(l.2)undertherest…     

关于Heisenberg流形Weyl律的余项(II)

研究$(2l+1)$维无理Heisenberg流形上Weyl律余项的平方积分均值, 并得到了渐近公式.     

含有三角函数的几个积分公式

本文给出含有三角函数的几个积分公式 ,使有关的运算变为更简捷 .一、有关公式定理　设 f ( x)在 [l,l +2 a]上可积 ,( a >0 ) ,则∫l+2 alf ( x) dx =∫l+al[f ( 2 l +2 a -x) +f ( x) ]dx. ( 1 )　　证明 ∫l+2 al f ( x) dx =∫l+al f ( x) dx +∫l+2 al+a f ( x) dx,∫l+2 al+af ( x) dx 令 x =2 l +2 a - tt[l,l +a]-∫la+lf ( 2 l +2 a -t) dt=∫l+al f ( 2 l +2 a -x) dx故∫l+2 al f ( x) dx =∫l+al [f ( 2 l +2 a -x) +f ( x) ]dx.合理地选择 2 a及 2 l,可使公式 ( 1 )在应用上极为方便 .我们给出公式 ( 1 )的一些特殊情况 (定…     

An Oscillation Criterion for Second Order Superlinear Differential Equations

61.IntroductionConsiderthesecondordersuperlinearequationx'(t) p(t)X'(t) q(t)1x(t)l"sgnx(t)=o,t>to,(1)wherea>l,pandq:[t,'co)-R=(-co,oo)arecontinuous.Weconsideronlysuchsolutionsxofequation(l)whichexistonsomeinterval[t.,oo),t.>t,>o.Asolutionofequation(l)issaidtobeoscillatoryifithasarbitrarilylargezerosandotherwise,itissaidtobenonoscillatory.Equation(l)iscalledoscillatoryifallofitssolutionsareoscilllatory.Forthespecialcasewherep(t)=Oli.e.,forthedifferentialequationx'(t) q(t)lx(t)l"sgnx(t)=o,a>1-…     

EXISTENCE OF POSITIVE SOLUTIONS TO(n-1,1)CONJUGATE BOUNDARY VALUE PROBLEMS

1IntroductionInarecentpaper[fi,P.W.EloeandJ.Hendersonstudiedtheexistenceofpositivesolutionsofthefollowingnonlinear(n--l,l)conjugateboundaryvalueproblem'TheworkwassupportedbyNSFofHeilonaiiangandNNSFofChinawheref:[0,co)-[0,co),a:[0,l]-[0,co)arecontinuousand…     

SOME ALMOST ALL RESULTS CONCERNINGTHE PJATECKII-SAPIRO PRIME NUMBERS

51.IntroductionSupposethatr>Oisafixednumberand[oldenotes,asusuaI,theintegralpartofo.LetForo1wasfirststudiedin1953byPjateckii-Sapiro[']whoprovedthat(1.1)holdsfor1相似文献   

P-Sasakian流形的外蕴球面(英)

本文讨论了P－Sasakian流形的外蕴球面，并给出了P－Sasakian流形的外蕴球面的一个分类定理．     

Second Order Parallel Tensors on P-Sasakian Manifolds

ＳｅｃｏｎｄＯｒｄｅｒＰａｒａｌｌｅｌＴｅｎｓｏｒｓｏｎＰ－ＳａｓａｋｉａｎＭａｎｉｆｏｌｄｓ￥ＤｅｂａｓｉｓｈＴａｒａｆｄａｒａｎｄＵ．Ｃ．Ｄｅ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＵｎｉｖｅｒｓｉｔｙｏｆＫａｌｙａｎｉ，Ｋａｌｙａｎｉ...     

ISOTROPIC WEYL MANIFOLD WITH A SEMI-SYMMETRIC CONNECTION

In this work,it is proved that every isotropic Weyl manifold with a semi- symmetric connection is locally conformal to an Einstein manifold with a semi-symmetric connection.     

广义典型流形的实例构作

陈述了广义典型流形(或拓扑域流形)的概念,并构作了拓扑域流形的若干实例,丰富了这类流形的内容,也给今后研究和运用拓扑域流形提供一些参考.     

On Flat Complete Causal Lorentzian Manifolds

We describe up to finite coverings causal flat affine complete Lorentzian manifolds such that the past and the future of any point are closed near this point. We say that these manifolds are strictly causal. In particular, we prove that their fundamental groups are virtually abelian. In dimension 4, there is only one, up to a scaling factor, strictly causal manifold which is not globally hyperbolic. For a generic point of this manifold, either the past or the future is not closed and contains a lightlike straight line     

Properties of the Michaelis-Menten mechanism in phase space

We study the two-dimensional reduction of the Michaelis-Menten reaction of enzyme kinetics. First, we prove the existence and uniqueness of a slow manifold between the horizontal and vertical isoclines. Second, we determine the concavity of all solutions in the first quadrant. Third, we establish the asymptotic behaviour of all solutions near the origin, which generally is not given by a Taylor series. Finally, we determine the asymptotic behaviour of the slow manifold at infinity. To this end, we show that the slow manifold can be constructed as a centre manifold for a fixed point at infinity.     

The Chern Conjecture for Affinely Flat Manifolds Using Combinatorial Methods

An affine manifold is a manifold with a flat affine structure, i.e. a torsion-free flat affine connection. We slightly generalize the result of Hirsch and Thurston that if the holonomy of a closed affine manifold is isomorphic to amenable groups amalgamated or HNN-extended along finite groups, then the Euler characteristic of the manifold is zero confirming an old conjecture of Chern. The technique is from Kim and Lee's work using the combinatorial Gauss–Bonnet theorem and taking the means of the angles by amenability. We show that if an even-dimensional manifold is obtained from a connected sum operation from K(, 1)s with amenable fundamental groups, then the manifold does not admit an affine structure generalizing a result of Smillie.     

Sasakian structures on CR-manifolds

A contact manifold M can be defined as a quotient of a symplectic manifold X by a proper, free action of \(\mathbb{R}\), with the symplectic form homogeneous of degree 2. If X is also Kähler, and its metric is homogeneous of degree 2, M is called Sasakian. A Sasakian manifold is realized naturally as a level set of a Kähler potential on a complex manifold, hence it is equipped with a pseudoconvex CR-structure. We show that any Sasakian manifold M is CR-diffeomorphic to an S ¹-bundle of unit vectors in a positive line bundle on a projective Kähler orbifold. This induces an embedding of M into an algebraic cone C. We show that this embedding is uniquely defined by the CR-structure. Additionally, we classify the Sasakian metrics on an odd-dimensional sphere equipped with a standard CR-structure.     

On Bochner flat para-Kählerian manifolds

Let B be the Bochner curvature tensor of a para-Kählerian manifold. It is proved that if the manifold is Bochner parallel (? B = 0), then it is Bochner flat (B = 0) or locally symmetric (? R = 0). Moreover, we define the notion of tha paraholomorphic pseudosymmetry of a para-Kählerian manifold. We find necessary and sufficient conditions for a Bochner flat para-Kählerian manifold to be paraholomorphically pseudosymmetric. Especially, in the case when the Ricci operator is diagonalizable, a Bochner flat para-Kählerian manifold is paraholomorphically pseudosymmetric if and only if the Ricci operator has at most two eigenvalues. A class of examples of manifolds of this kind is presented.     

关于近Hermitian流形的注记(英文)

We give a necessary and sufficient condition for an almost Hermitian manifold to be a Kahler manifold. By making use of this condition, we give a new proof of Goldberg＇s theorem.