共查询到20条相似文献,搜索用时 78 毫秒
1.
具有正负系数的中立型方程的振动性 总被引:7,自引:0,他引:7
讨论中立型方程d/dt[x(t)-R(t)x(t-r)] P(t)x(t-t)-Q(t)x(t-δ)=0,(*)其中P,Q,R∈C[(to,∞),R∧ ),r,τ,δ∈(0,∞),τ≥δ,在允许R(t) ∫∧tt=τ δQ(u)du-1变号的情况下得到(*)的所有解振动的判据。 相似文献
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考虑二阶中立型时滞微分方程[a(t)|(x(t) p(t)x(t-τ))′|^α-1(x(t) p(t)x(t-τ))′]′ f(t,x(t-σ))=0(E)其中α,τ,σ是非负常数,a(t),p(t)∈C([t0,∞),R),f(t,x)∈C(R,R)。建立了方程(E)的一些新的振动条件。 相似文献
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关于高阶中立型泛函微分方程的振动性 总被引:1,自引:0,他引:1
陈永劭 《高校应用数学学报(A辑)》1992,7(2):294-302
本文研究了中立型泛函微分方程 d~n/dt~n[x(t)+cx(t-τ)]+p(t)x(t-σ)=0的振动性,这里c,τ,σ∈R,n≥2,τ≥0,σ≥0,p(t)是在[T,+∞)上的连续函数,且p(t)≥0,我们得到了在c≥0,一1≤c<0和c<一1等情况下方程振动的若干充分性条件. 相似文献
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本文对较文[1,2]中更为广泛的具有非正系数的一类线性方程d/(dt)[x(t)+p(t)x(t-τ)]-Q(t)x(t-σ(t))=0,t≥t0及非线性方程d/(dt)[x(t)+p(t)x(t-τ(t))]-Q(t)f(x(t-σ(t)))=0,t≥t0进行了讨论,其中Q(t)∈C([t0,+∞).R+),得到了保证上述方程的所有有界解振动及非振动解当t→+∞时趋于零或±∞的一些充分性准则. 相似文献
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考虑中立型微分方程dndtn[x( t) -P( t) x( t-τ) ]+Q( t) x( t-σ) =0 , t≥ t0 ,( * )其中 n≥ 1 ,n为奇数 ,P( t) ,Q( t)∈ C( [t0 ,+∞ ) ,R+ ) τ>0 ,σ>0 .本文在不需要通常假设 ∫∞t0Q( s) ds=∞的条件下 ,获得了保证 ( * )的所有解振动的几个充分条件 ,并推广了文 [1 ]、[3]的相应结论 . 相似文献
6.
本文研究非线性中立型时滞微分方程N( t) =N( t) [a( t) -b( t) N ( t-τ) -c( t) N( t-σ) -d( t) N ( t) ],t≥ t0 ,( E)其中τ,σ∈ [0 ,∞ ) ,a( t) ,b( t) ,d( t)∈ C1( [t0 ,∞ ) ,R+) ,c( t)∈ C( [t0 ,∞ ) ,k) ,得到方程 ( E)的正解关于正常数平衡点全局渐近稳定和振动的充分条件 .本文所用方法与其他文献不同 ,所得结果发展了一些文献的结果 ,其中定理 ( 2 .3)回答了由 Y.Kuang and A.Feldstein所提出的一个公开问题 . 相似文献
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研究时滞微分方程x′(t) p(t) x(t-τ) =0 ,t≥ t0 , (1)(x(t) a(t) x(t-δ) )′ b(t) x(t-σ) =0 ,t≥ t0 ,(2 )的解的零点距 .采用一种新方法 ,给出其解任意两相邻零点之间的距离的估计 ,改进、推广已有的结果 相似文献
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§1. IntroductionThispaperisconcernedwiththeasymptoticbehavioroftheoscillatorysolutionsofnonlin-earforcedneutraldelaydifferentialequationsoftheform[x(t)-∑mi=1pi(t)x(t-τi)]′ ∑nj=1qj(t)f(x(t-σj))=r(t), t≥t0,(1)wherepi,qj,r∈C([t0,∞),R),τi,σj≥0,i=1,2,…,m;j=1,2,…,n,f∈C(R,R),xf(x)>0forx≠0.Whenpi(t)≡0,i=1,2,…,m,Eq.(1)reducestox(t) ∑nj=1qj(t)f(x(t-σj))=r(t), t≥t0,(2)whoseasymptoticbehaviorofallsolutionshasbeenstudiedinJ.R.Yan[5].Whenr(t)≡0,f(x)≡xandm=n=1,Eq.(1)reducesto[… 相似文献
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Jogi Henna 《Annals of the Institute of Statistical Mathematics》2005,57(4):655-664
An estimator of the number of components of a finite mixture ofk-dimensional distributions is given on the basis of a one-dimensional independent random sample obtained by a transformation
of ak-dimensional independent random sample. A consistency of the estimator is shown. Some simulation results are given in a case
of finite mixtures of two-dimensional normal distributions. 相似文献
12.
N/Kbe a Galois extension of number fields with finite Galois group G.We describe a new approach for constructing invariants of the G-module structure of the K groups of the ring of integers of N in the Grothendieck group of finitely generated projective Z[G]modules. In various cases we can relate these classes, and their function field counterparts, to the root number class of Fröhlich and Cassou-Noguès. 相似文献
13.
Piotr Je¸drzejewicz 《代数通讯》2013,41(4):1500-1508
Let A be a UFD of characteristic p > 0, let 𝒵 be a set of some eigenvectors of a derivation of A. We prove, under some additional assumptions, a necessary and sufficient condition for 𝒵 to be a p-basis of the minimal ring of constants containing 𝒵. The main preparatory result is the unique decomposition theorem with respect to a factor from a given subalgebra containing Ap. 相似文献
14.
有资格限制的指派问题的求解方法 总被引:3,自引:0,他引:3
在实际的指派工作中,常会遇到某个人有没有资格去承担某项工作的问题,因此,本建立了有资格限制的指派问题的数学模型。在此数学模型中,将效益矩阵转化为判定矩阵,由此给出了判定此种指派问题是否有解的方法;在有解的情况下,进一步将效益矩阵转化为求解矩阵,从而将有资格限制的指派问题化为传统的指派问题来求解。最后给出了一个数值例子来说明这样的处理方法是有效的。 相似文献
15.
We study the nilpotency of the sums of all coefficients of some sorts of products of polynomials over reversible, IFP, and NI rings, and introduce an SCN ring as a generalization. We characterize SCN rings in relation with related ring properties, and also provide several useful properties and ring extensions of SCN rings. 相似文献
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In this paper we determine the minimum and maximum values of the sum of squares of degrees of bipartite graphs with a given number of vertices and edges. 相似文献
17.
Rodney Y. Sharp 《Proceedings of the American Mathematical Society》2003,131(10):3009-3017
It is a well-known result of M. Brodmann that if is an ideal of a commutative Noetherian ring , then the set of associated primes of the -th power of is constant for all large . This paper is concerned with the following question: given a prime ideal of which is known to be in for all large integers , can one identify a term of the sequence beyond which will subsequently be an ever-present? This paper presents some results about convergence of sequences of sets of associated primes of graded components of finitely generated graded modules over a standard positively graded commutative Noetherian ring; those results are then applied to the above question.
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Nguyêñ Quoôć Thǎ;ńg 《代数通讯》2013,41(3):1097-1110
We present a unified approach to compute the number of connected components in the group of real points of adjoint almost simple real algebraic groups. 相似文献
20.
Janusz Sokó? 《Journal of Mathematical Analysis and Applications》2008,344(2):869-875
We consider the classes of analytic functions introduced recently by K.I. Noor which are defined by conditions joining ideas of close-to-convex and of bounded boundary rotation functions. We investigate coefficients estimates and radii of convexity. 相似文献