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1.
三阶泛函微分方程的周期解   总被引:2,自引:0,他引:2  
利用Brouwer度理论得到了泛函微分方程x′″(t) ∑i=0^2[αix(i)(t) bix(i)(t-τi)] g1(x(t)) g2(x(t-τ))=p(t)存在2π周期解的充分性条件,推广了[1]中的有关结果.  相似文献   

2.
一类积分微分方程周期解的存在性和唯一性   总被引:13,自引:1,他引:12  
本文考虑具连续时滞和离散时滞的非线性积分微分方程x'(t)=A(t,x(t))x(t)+∫-∞tC(t,s)x(s)ds+∑i=1i gi(t,x(t—τi(t)))+b(t)和x’(t)=f(t,x(t))+∫-∞tC(t,s)x(s)ds+∑i=1igi(t,x(t-τi(t)))+b(t)周期解的存在性和唯一性问题,这里t∈R,x∈Rn;A(t,x),C(t,s)为n×n阶连续的函数矩阵; f(t,x),gi(t,x)(i=1,2,…,l),b(t)是n维连续向量.通过利用线性系统指数型二分性理论和泛函分析方法研究上述系统,获得了保证其周期解存在性、唯一性的充分性条件.我们除了实质性的推广和改进了已有的结果外,还得到三个新的定理,这是用已有的方法无法获得的(见文[1-30]).  相似文献   

3.
一类三阶泛函微分方程周期解的存在唯一性   总被引:2,自引:0,他引:2  
利用重合度理论研究了一类三阶泛函微分方程x′′′(t)+multiply from i=1 to 2[a_ix~((i))+b_ix~((i))(t-τ_i)]+ g_1(x(t))+g_2(x(t-τ))=p(t)的2π-周期解问题,获得了该方程2π-周期解存在唯一性的若干新结论.  相似文献   

4.
利用重合度理论研究了一类高阶Duffing方程x(m)(t)+β(t)x'(t)+g(t,x(t))=e(t),得到了周期解存在性和唯一性的一些结论.有意义的是线性项前的系数β(t)可变号,这在现有的文献中是很少见到的.  相似文献   

5.
Let→b=(b1,b2,…,bm),bi∈∧βi(Rn),1≤I≤m,βi>0,m∑I=1βi=β,0<β<1,μΩ→b(f)(x)=(∫∞0|F→b,t(f)(x)|2dt/t3)1/2,F→b,t(f)(x)=∫|x-y|≤t Ω(x,x-y)/|x-y|n-1 mΠi=1[bi(x)-bi(y)dy.We consider the boundedness of μΩ,→b on Hardy type space Hp→b(Rn).  相似文献   

6.
奇异半线性反应扩散方程组Cauchy问题   总被引:1,自引:0,他引:1  
本文讨论如下问题其中{(б)u/(б)t-(1/tσ)△u=αvp1+β1vp1+f1(x),t>0,x∈RN,(б)u/(б)t-(1/tσ)△v=α2uq2+β2vp2+f2(x),t>0,∈RN,limt→0+u(t,x)=limt→0+v(t,x)=0,x∈Rn,其中σ>0,pi>1,qi>1(i=1,2),α1≥0,α2>0,β1>0,β2≥0,fi(x)(i=1,2)连续有界非负,(f1(x),f2(x))(≡/)(0,0).给出了非负局部解存在的几个充分条件和解的爆破结果.  相似文献   

7.
考虑具连续时滞和离散时滞的中立型积分微分方程d/dt[x(t) q∑j=1ej(t)x(t-δj(t))]=A(t,x(t))x(t ∫t-∞ C(t,s)x(s)ds 1∑i=1gi(t,x(t-Υi(t))) b(t)和d/dt[x(t) q∑j=1ej(t)x(t-δj(t))]=A(t)x(t) ∫t-∞C(t,s)x(s)ds 1∑j=1gi(t,x(t-Υi(t))) b(t)周期解的存在性和唯一性问题,利用线性系统指数型二分性理论和泛函分析方法,并通过技巧性代换获得了保证中立型系统周期解存在性和唯一性的充分性条件,从而避开了在研究中立型系统时x(t-δ)时滞项的导数x1(t-δ)的出现,推广了相关文献的主要结果.  相似文献   

8.
鲁世平 《数学研究》2000,33(3):292-297
利用Fouier级数理论和不动点原理研究下列方程:d^n/dt^n(x(t)-cs(t-τ))=n/∑/j=1ajx^(n-j)(t) n/∑/j=1bjx(n-j)t-τ) f(t,xt,x′t,…,x^(n-1)t)的周期解问题,得到了解的存在性和唯一性。  相似文献   

9.
一类二阶泛函微分方程周期解存在性问题   总被引:18,自引:0,他引:18  
任景莉  葛渭高 《数学学报》2004,47(3):569-578
利用重合度理论研究一类二阶泛函微分方程x″(t)+f(t,x_t)x′~n+β(t)g(x(t-τ(t)))=p(t)的周期解问题,本文得到了周期解存在的新的结果。  相似文献   

10.
本文研究含有n 个滞量的三维微分差分方程组x(t)=sum from i=1 to ∞(1/i)f[x(t),x(t-τ_i),y(t),y(t-τ_i),z(t),z(t-τ_i)]y(t)=sum from i=1 to ∞(1/i)g[x(t),x(t-τ_i),y(t),y(t-τ_i),z(t),z(t-τ_i)](τ_i>0)z(t)=sum from i=1 to ∞(1/i)h[x(t),x(t-τ_i),y(t),y(t-τ_i),z(t),z(t-τ_i)]周期解的存在性,给出了方程组周期解周期的取值范围.推广并改进了文[1]的结果.  相似文献   

11.
12.
基础学科的教材直接影响学生的基本功,尤其是几乎每个学科都会涉及的数学类教材,如矩阵论.矩阵论是研究生的基础课程,在对学生以后的学术道路有举足轻重的作用.所以选择一本合适的教材,对学生和教师来说都有不小的帮助.然而,对教材的评价而言,不能单单从一个方面入手,因此将模糊综合分析法与层次分析法结合,在矩阵论教材的评价方面建立评价体系,为高校选择合适的教材提供依据.  相似文献   

13.
The central purpose of this paper is to illustrate that combining the recently developed theory of random conjugate spaces and the deep theory of Banach spaces can, indeed, solve some difficult measurability problems which occur in the recent study of the Lebesgue (or more general, Orlicz)-Bochner function spaces as well as in a slightly different way in the study of the random functional analysis but for which the measurable selection theorems currently available are not applicable. It is important that this paper provides a new method of studying a large class of the measurability problems, namely first converting the measurability problems to the abstract existence problems in the random metric theory and then combining the random metric theory and the relative theory of classical spaces so that the measurability problems can be eventually solved. The new method is based on the deep development of the random metric theory as well as on the subtle combination of the random metric theory with classical space theory.  相似文献   

14.
Based on the theory of micromorphic fluid dynamics (MMF), a new theory of turbulence is introduced. The law of conservation of microinertia of MMF is replaced by a balance law of microinertia, with all other laws remaining unchanged, the theory is called, “extended micromorphic fluid dynamics”. The present theory of turbulence is founded on the extended theory. Thus, a new theory of turbulence, is founded on the first principles, not using any a priori closure assumptions or semi-empirical hypothesis. Field equations are solved for the two-dimensional steady channel flow. The mean velocity turbulent shear stress and all turbulent velocities are in remarkably good agreement with the experimentally observed turbulent velocities.  相似文献   

15.
We consider an explicitly covariant formulation of the quantum field theory of the Maslov complex germ (semiclassical field theory) in the example of a scalar field. The main object in the theory is the “semiclassical bundle” whose base is the set of classical states and whose fibers are the spaces of states of the quantum theory in an external field. The respective semiclassical states occurring in the Maslov complex germ theory at a point and in the theory of Lagrangian manifolds with a complex germ are represented by points and surfaces in the semiclassical bundle space. We formulate semiclassical analogues of quantum field theory axioms and establish a relation between the covariant semiclassical theory and both the Hamiltonian formulation previously constructed and the axiomatic field theory constructions Schwinger sources, the Bogoliubov S-matrix, and the Lehmann-Symanzik-Zimmermann R-functions. We propose a new covariant formulation of classical field theory and a scheme of semiclassical quantization of fields that does not involve a postulated replacement of Poisson brackets with commutators.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 3, pp. 492–512, September, 2005.  相似文献   

16.
The notion of a fusion system was first defined and exploredby Puig in the context of modular representation theory. Later,Broto, Levi, and Oliver significantly extended the theory offusion systems as a tool in homotopy theory. In this paper webegin a program to establish a local theory of fusion systemssimilar to the local theory of finite groups. In particular,we define the notion of a normal subsystem of a saturated fusionsystem, and prove some basic results about normal subsystemsand factor systems.  相似文献   

17.
In this paper we develop the fundamental elements and results of a new theory of regular functions of one quaternionic variable. The theory we describe follows a classical idea of Cullen, but we use a more geometric formulation to show that it is possible to build a rather complete theory. Our theory allows us to extend some important results for polynomials in the quaternionic variable to the case of power series.  相似文献   

18.
Formal theories, as in logic and mathematics, are sets of sentences closed under logical consequence. Philosophical theories, like scientific theories, are often far less formal. There are many axiomatic theories of the truth predicate for certain formal languages; on analogy with these, some philosophers (most notably Paul Horwich) have proposed axiomatic theories of the property of truth. Though in many ways similar to logical theories, axiomatic theories of truth must be different in several nontrivial ways. I explore what an axiomatic theory of truth would look like. Because Horwich’s is the most prominent, I examine his theory and argue that it fails as a theory of truth. Such a theory is adequate if, given a suitable base theory, every fact about truth is a consequence of the axioms of the theory. I show, using an argument analogous to Gödel’s incompleteness proofs, that no axiomatic theory of truth could ever be adequate. I also argue that a certain class of generalizations cannot be consequences of the theory.  相似文献   

19.
Based on the theory of micromorphic fluid dynamics (MMF), a new theory of turbulence is introduced. The law of conservation of microinertia of MMF is replaced by a balance law of microinertia, with all other laws remaining unchanged, the theory is called, “extended micromorphic fluid dynamics”. The present theory of turbulence is founded on the extended theory. Thus, a new theory of turbulence, is founded on the first principles, not using any a priori closure assumptions or semi-empirical hypothesis. Field equations are solved for the two-dimensional steady channel flow. The mean velocity turbulent shear stress and all turbulent velocities are in remarkably good agreement with the experimentally observed turbulent velocities.  相似文献   

20.
An iterative analytical theory in the mechanics of layered composite systems is developed. The prehistory of the nonclassical theory of layered systems is presented. The division of this theory into two principal directions - discrete-structural and continuous-structural - is mentioned. The basic iterative Ambartsumyan theory, which belongs to the second direction, is described. The formation of the generalized iteration theory of first approximation is shown. In this theory, the disagreement between the kinematic and static models is removed, i.e., a generalization of these models is realized. The theory of second approximation is described. An iterative principle is presented for the formation of a higher-approximation nonclassical theory. Based on this principle, theories of anisotropic composite shallow shells, plates, and beams are formulated. Comparative calculation results for different layered composite systems are presented.  相似文献   

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