共查询到20条相似文献,搜索用时 15 毫秒
1.
Alexander Fischer 《Czechoslovak Mathematical Journal》1998,48(2):193-205
It is not the purpose of this paper to construct approximations but to establish a class of almost periodic functions which can be approximated, with an arbitrarily prescribed accuracy, by continuous periodic functions uniformly on =(+). 相似文献
2.
A. Yu. Ol'shanskii 《Ukrainian Mathematical Journal》1992,44(6):761-763
It is proved that each periodic group is isomorphic to a subgroup of some simple periodic group.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 44, No. 6, pp. 845–847, June, 1992. 相似文献
3.
Masoud Hajarian 《Mathematical Methods in the Applied Sciences》2019,42(10):3527-3548
Analysis and design of linear periodic control systems are closely related to the periodic matrix equations. The objective of this paper is to provide four new iterative methods based on the conjugate gradient normal equation error (CGNE), conjugate gradient normal equation residual (CGNR), and least‐squares QR factorization (LSQR) algorithms to find the reflexive periodic solutions (X1,Y1,X2,Y2,…,Xσ,Yσ) of the general periodic matrix equations for i = 1,2,…,σ. The iterative methods are guaranteed to converge in a finite number of steps in the absence of round‐off errors. Finally, some numerical results are performed to illustrate the efficiency and feasibility of new methods. 相似文献
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Inventiones mathematicae - 相似文献
6.
This paper discusses a discrete Lotka-Volterra competition system. We first obtain the persistence of the system. Assuming that the coefficients in the system are periodic, we obtain the existence of a periodic solution. Moreover, under some additional conditions, this periodic solution is globally stable. Our results not only reduce to those for the scalar equation when there is no coupling but also improve and complement some in the literature. 相似文献
7.
In this paper, we characterize periodic solutions of p-periodic difference equations. We classify the periods into multiples of p and nonmultiples of p. We show that the elements of the set of multiples of p follow the well-known Sharkovsky’s ordering multiplied by p. On the other hand, we show that the elements of the set Γp of nonmultiples of p are independent in their existence. Moreover, we show the existence of a p-periodic difference equation with infinite Γp-set in which the maps are defined on a compact domain and agree exactly on a countable set. Based on the proposed classification, we give a refinement of Sharkovsky’s theorem for periodic difference equations. 相似文献
8.
In this work we show that the Wecken theorem for periodic points holds for periodic homeomorphisms on closed surfaces, which therefore completes the periodic point theory in such a special case. Using it we derive the set of homotopy minimal periods for such homeomorphisms. Moreover we show that the results hold for homotopically periodic self-maps of closed surfaces. This let us to re-formulate our results as a statement on properties of elements of finite order in the group of outer automorphisms of the fundamental group of a surface with non-positive Euler characteristic. 相似文献
9.
We consider a class of nonlinear periodic evolution equations, leaving invariant a cone in a real Banach space, and satisfying appropriate monotonicity requirements. A necessary and sufficient condition is found for the existence of a (unique, globally attractive) nontrivial periodic solution within the cone. Such a condition is expressed in terms of an associated linear equation. To establish this result, an abstract version of the familiar comparison techniques for parabolic equations is worked out. Applications and examples are also discussed. 相似文献
10.
Zhi-Han Zhao Yong-Kui Chang Wen-Sheng Li 《Nonlinear Analysis: Real World Applications》2010,11(4):3037-3044
In this paper we establish the existence and uniqueness of almost periodic, asymptotically almost periodic and pseudo-almost periodic mild solutions for neutral differential equations in Banach spaces. 相似文献
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12.
Global dynamics of the periodic logistic system with periodic impulsive perturbations 总被引:1,自引:0,他引:1
This paper studies the global behaviors of the periodic logistic system with periodic impulsive perturbations. The results of D.D. Bainov and P.S. Simeonov (1993) are extended and dynamics different from the corresponding continuous system are found. It is shown that the system may have a unique positive periodic solution which is globally asymptotically stable, or go extinct when the two periods are rational dependent. When they are rational independent, the system has no periodic solutions, however, still has a global attractor or go extinct under some conditions. 相似文献
13.
Wenke Tan 《Journal of Functional Analysis》2011,261(5):1204-1226
In the paper, we first show the existence of global periodic conservative solutions to the Cauchy problem for a periodic modified two-component Camassa-Holm equation. Then we prove that these solutions, which depend continuously on the initial data, construct a semigroup. 相似文献
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15.
Yongli Song 《Applicable analysis》2013,92(11):1095-1101
By using the continuation theorem of coincidence degree theory by Gaines and Mawhin, a sufficient and realistic condition is obtained for the existence of a periodic survival red blood cell model. 相似文献
16.
A. Yu. Ol'shanskii 《Ukrainian Mathematical Journal》1991,43(7-8):914-919
We prove a theorem on the isomorphic imbedding of an arbitrary countable periodic group H into a simple 2-generated periodic group G. In addition, we show that for any integers k 2 and 3 the group G contains a pair of generating elements whose orders are k and .Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, Nos. 7 and 8, pp. 980–986, July–August, 1991. 相似文献
17.
In this paper, the backward error of periodic invariant subspaces for regular periodic pairs is defined and its explicit expression is derived. In particular, we also present the expression of the backward error of generalized invariant subspaces for the regular matrix pair. The results are illustrated by two numerical examples. 相似文献
18.
Jurang Yan 《Journal of Mathematical Analysis and Applications》2009,356(1):288-4959
In this paper, an easily verifiable necessary and sufficient condition for the existence of positive periodic solutions of generalized n-species Lotka-Volterra type and Gilpin-Ayala type competition systems is obtained. It improves a series of the well-known sufficiency theorems in the literature about the problems mentioned above. The method is based on a well-known fixed point theorem in a cone of Banach space. This approach can be applied to more general competition systems. 相似文献
19.
Sufficient conditions for the existence of at least one periodic solution of two classes of nonlinear higher order periodic difference equations are established, respectively. The results show us that sufficient conditions for the existence of T ? periodic solutions of difference equation are different from those ones for the existence of T ? periodic solutions of differential equation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
An SEIR model with periodic coefficients in epidemiology is considered. The global existence of periodic solutions with strictly positive components for this model is established by using the method of coincidence degree. Furthermore, a sufficient condition for the global stability of this model is obtained. An example based on the transmission of respiratory syncytial virus (RSV) is included. 相似文献