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1.
二阶泛函常微分方程解的振动性与非振动性   总被引:2,自引:0,他引:2  
对于二阶线性常微分方程由Sturm定理知,方程(1)的解或者都是振动、或者都是非振动。所谓一个解y(t)为振动的,是指当t→∞时,y(t)具有没有尽头的零点。于是,非振动解y(t)是指存在某一有限时刻T,当t>T后,y(t)不再有零点。  相似文献   

2.
带强迫项高阶中立型微分方程的振动性和非振动性   总被引:1,自引:0,他引:1  
我们给出一类强迫高阶非线性中立型时滞微分方程一切解振动的充分条件.而且,也研究了一类强迫一阶中立型方程非振动解的渐近性.  相似文献   

3.
证明了线性脉冲中立型时滞微分方程解的振动性等价于一类非脉冲中立型时滞微分方程解的振动性,应用这一结果建立了此类线性脉冲中立型微分方程解的振动性的显示判据。  相似文献   

4.
考虑具有脉冲扰动的造血模型,得到了方程非振动解的渐近性及所有解关于平衡点K振动的充分条件,推广了文献中的相关结论.  相似文献   

5.
本文考虑一类非线性延迟微分方程-带有单峰造血率的造血模型数值解的振动性及非振动性。运用线性化理论,把非线性差分方程的振动性转化为其对应的线性差分方程的振动性,通过判断线性方程的特征方程根的情况,得到了非线性差分方程振动和存在非振动解的充分条件。对于非振动的数值解,证明了非振动的数值解最终都趋于方程的平衡解。为了更有力的说明我们的结果给出了相应的算例.  相似文献   

6.
双曲偏泛函微分方程解的振动性   总被引:6,自引:0,他引:6  
讨论了一类双曲偏泛函微分方程解的振动性,给出了在三类边界条件下解的振动准则  相似文献   

7.
主要考虑了一类红细胞模型数值解的振动性,通过振动性的理论将非线性延迟微分方程转化为相应的线性延迟微分方程,再利用线性θ-方法,得到相应的差分方程,从而得到数值解振动的条件以及非振动解的渐近性质.为了更好的说明结果,最后给出了一些算例.  相似文献   

8.
在α>1,且0<β<α情性下研究了高阶具非线性中立项不稳定型时滞微分方程[x(t)-pxα(t-τ)](n)=q(t)xβ(t-σ),(t≥t0)的振动和非振动性.利用一些新的技巧,获得了上述方程有界解振动的振动准则和至少存在一个非振动解的非振动准则,所得结果补充和推广了已有文献部分结果.  相似文献   

9.
脉冲中立型时滞微分方程的振动性   总被引:12,自引:0,他引:12  
燕居让 《数学年刊A辑》2000,21(6):755-762
本文证明了线性脉冲中立型微分方程解的振动性等价于一类线性非脉冲中立型时滞微分方程解的振动性.应用这一结果,建立了线性脉冲中立型方程解振动性的显式判据.这些判别条件,显著地改进了已有的结果.  相似文献   

10.
脉冲中立型时滞微分方程的振动性   总被引:9,自引:0,他引:9  
本文证明了线性脉冲中立型微分方程解的振动性等价于一类线性非脉冲中立型时滞微分方程解的振动性.应用这一结果,建立了线性脉冲中立型方程解振动性的显式判据.这些判别条件,显著地改进了已有的结果.  相似文献   

11.
Multiple solutions are reported for the two-dimensional boundary layer flow of a viscous fluid near a permeable wall through which fluid is uniformly withdrawn. In the limit of large wall suction, three flows of similarity form are found: the first is the well-known monotonic solution of Terrill; the second exhibits flow reversal, with the streamlines being separated into three distinct cells; the third also exhibits flow reversal, but has multiple cells only when the fluid withdrawal speed is less than some threshold. The wall injection problem is also briefly studied, only Terrill's branch of solutions being found. Numerical and asymptotic solutions are presented and compared; the large-suction asymptotics of the third solution branch are found to be rather subtle.  相似文献   

12.
关于工科“线性代数”课程中的反问题   总被引:1,自引:0,他引:1  
讨论了工科"线性代数"课程中涉及到的几类简单的反问题,给出了解的存在条件与一般解法.  相似文献   

13.
对2004年首届研究生数学建模竞赛的C题“售后服务数据的运用”在竞赛中学生们做出的各种作法给予了评述,同时给出评卷时的评分标准和一个参考解答.  相似文献   

14.
利用上下解方法及单调迭代技术讨论了一类具有上确界的二阶非线性脉冲微分方程无穷边值问题,给出了其最小最大解存在定理.  相似文献   

15.
Abstract With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree,westudy the global existence of positive periodic solutions of a "food-limited" population model with toxicants andtime delays.Some new results are obtained.  相似文献   

16.
高凌云 《数学季刊》2003,18(3):230-233
§ 1. Introduction  Inthispaperwewillconsidertheproblemoftheformofalgebraicdifferentialequationwithadmissiblemeromorphicsolution[Ω1 (z ,w) /Ω2 (z ,w) ] m =∑nj=0aj(z)wj,(1 )whereΩ1 (z,w) =∑(i)a(i) (z)wi0 (w′) i1… (w(n) ) in,Ω2 (z,w) =∑( j)b( j) (z)wj0 (w′) j1… (w(n) ) jn,(i) ,(j)arefiniteindexsets,{ai(z) } ,{a(i) (z) }and {a(i) (z) }aremeromorphicfunctions,T(r,a(i) ) =o(T(r,w) ) ,T(r,ai) =o(T(r ,w) ) ,T(r,b(j) ) =o(T(r ,w) ) .Letw(z)beameromorphicsolutionof (1 ) .Ifw(z)satisfies…  相似文献   

17.
We use Brouwer degree to prove existence and multiplicity results for the periodic solutions of some nonlinear second order difference equations involving discrete -Laplacian. We obtain in particular upper and lower solutions theorems, Ambrosetti–Prodi type multiplicity results, sharp existence conditions for nonlinearities which are bounded from below or from above and necessary and sufficient conditions for the existence of positive periodic solutions when the nonlinearity is singular at 0.  相似文献   

18.
In discrete maximization problems one usually wants to find an optimal solution. However, in several topics like “alignments,” “automatic speech recognition,” and “computer chess” people are interested to find thekbest solutions for somek ≥ 2. We demand that theksolutions obey certain distance constraints to avoid that thekalternatives are too similar. Several results for valuated -matroids are presented, some of them concerning time complexity of algorithms.  相似文献   

19.
1IntroductionInthispaperweconsiderthefollowingneutraldifferentialequationwherep9T)aarepositive,gEC(R ,R)andA7g(t)=oo,andfeC(R xR',R).WeshallassumethatthereexistsafunctionF(t,u,v)6C(R;,R )suchthatFisnondecreasinginuandvandWeshallnotethatequationswithmaximaoccurintheproblemofautomaticregulationofvariousrealsystems[4],[6].Themaximaariseswhentheregu-lationlawcorrespondstothemaximaldeviationoftheregurablequantity.Ourmaingoalwillbetoestablishsufficientconditionsfortheexistenceofoscillatorysol…  相似文献   

20.
Abstract. We consider the Navier-Stokes equations with time-dependent external force, either in the whole time or in positive time with initial data, with domain either the whole space, the half space or an exterior domain of dimension . We give conditions on the external force sufficient for the unique existence of small solutions in the weak- space bounded for all time. In particular, this result gives sufficient conditions for the unique existence and the stability of small time-periodic solutions or almost periodic solutions. This result generalizes the previous result on the unique existence and the stability of small stationary solutions in the weak- space with time-independent external force. Received: 30 March 1999 / Accepted: 21 September 1999 / Published online: 28 June 2000  相似文献   

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