Periodicity in a “Food-limited” Population Model with Toxicants and Time Delays

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.     

POSITIVE PERIODIC SOLUTIONS OF A CLASS OF DISCRETE TIME SYSTEM WITH DELAYS AND A FEEDBACK CONTROL

With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, sufficient conditions are established for the existence of periodic solutions of a class of discrete differential system with delays and feedback control.     

具有状态反馈控制的合作系统的周期解（英文）

In this paper,we propose a semi-continuous dynamical system to study the cooperative system with feedback control.Based on geometrical analysis and the analogue of Poincaré criterion,the existence and stability of the positive order one periodic solutions are given.Numerical results are carried out to illustrate the feasibility of our main results.     

DYNAMICS OF THE NONAUTONOMOUS SCHONER MODEL WITH FEEDBACK CONTROL AND DIFFUSION

This paper consider a nonautonomous schoner model with feedback control and diffusion. It is shown that the system can be made persistence. Then the existence and the uniqueness of the positive solutions and positive almost periodic solutions for corresponding periodic system and almost periodic system are also discussed.     

Positive periodic solution for a nonautonomous periodic model of population with time delays and impulses

In this paper, a nonautonomous periodic model of population with time delays and impulses, which arises in order to describe the control of a single population of cells, is studied. By the coincidence degree theory we obtain the conditions for the existence of periodic solution of this system.     

PERMANENCE OF A DISCRETE SINGLE SPECIES SYSTEM WITH DELAYS AND FEEDBACK CONTROL

In this paper,a discrete single species system with time delays and feedback control is considered.Sufficient conditions which guarantee the permanence of all positive solutions to this discrete system are obtained.The results show that the feedback control is harmless for the permanence of the species.     

OPTIMAL EXISTENCE THEORY FOR SINGLE AND MULTIPLE POSITIVE PERIODIC SOLUTIONS TO FUNCTIONAL DIFFERENCE EQUATIONS WITH FEEDBACK CONTROL

Using a fixed point theorem in a cone, we obtain some optimal existence results for single and multiple positive periodic solutions to a functional difference system with feedback control. Moreover, we apply our results to a population model.     

EXISTENCE OF POSITIVE PERIODIC SOLUTION OF MUTUALISM SYSTEM WITH INFINITE DELAYS

In this paper, by using Mawhin coincidence degree, some sufficient conditions are obtained for the global existence of positive periodic solution of a mutualism system with infinite delays. Our results generalize those of Yang etc. [8] and Gopalsamy and He [7].     

ON A PERIODIC VOLTERRA EQUATION WITH SEVERAL FINITE DELAYS AND AN INFINITE DELAY

The existence of positive periodic solutions for a periodic Volterra equation with several finite delays and an infinite delay is established. Sufficient conditions for the periodic solutions having global attractivity are obtained.     

POSITIVE PERIODIC SOLUTION TO A CLASS OF NONLINEAR PERIODIC DIFFERENTIAL EQUATION WITH IMPULSES AND DELAY

In this paper, by using a fixed point theorem of Krasnoselskii, we study the positive periodic solution for a class of nonlinear periodic differential equation with impulses and delay. Firstly, definition of periodic solution and some lemmas are stated. Then some results of the existence of positive periodic solution about the equation are obtained.     

Degenerate Orbit Flip Homoclinic Bifurcations with Higher Dimensions

Bifurcations of a degenerate homoclinic orbit with orbit flip in high dimensional system are studied. By establishing a local coordinate system and a Poincaré map near the homoclinic orbit, the existence and uniqueness of 1–homoclinic orbit and 1–periodic orbit are given. Also considered is the existence of 2–homoclinic orbit and 2–periodic orbit. In additon, the corresponding bifurcation surfaces are given. Project supported by the National Natural Science Foundation of China (No: 10171044), the Natural Science Foundation of Jiangsu Province (No: BK2001024), the Foundation for University Key Teachers of the Ministry of Education of China     

Ideals in Morita Rings and Morita Semigroups

We characterize the lattice of all ideals of a Morita ring （semigroup） when the corresponding pair of rings （semigroups） in the Morita context are Morita equivalent s-unital （like-unitv） rings （semigroups）.     

Global solutions of stochastic 2D Navier-Stokes equations with Lévy noise

In this paper, we prove the global existence and uniqueness of the strong and weak solutions for 2D Navier-Stokes equations on the torus perturbed by a Lévy process. The existence of invariant measure of the solutions are proved also. This work was supported by National Basic Research Program of China (Grant No. 2006CB8059000), Science Fund for Creative Research Groups (Grant No. 10721101), National Natural Science Foundation of China (Grant Nos. 10671197, 10671168), Science Foundation of Jiangsu Province (Grant Nos. BK2006032, 06-A-038, 07-333) and Key Lab of Random Complex Structures and Data Science, Chinese Academy of Sciences     

Existence,uniqueness and stability of positive steady states to a prey-predator diffusion system

In the paper, we study the positive solutions of an elliptic system coming from a preypredator model with modified Leslie-Gower and Holling-Type II schemes. We study the existence, non-existence, bifurcation, uniqueness and stability of positive solutions. In particular, we obtain a continuum of positive solutions connecting a semi-trivial solution to the unique positive solution of the limiting system. This work was supported by National Natural Science Foundation of China (Grant Nos. 10471022, 10771032) and Natural Science Foundation of Jiangsu Province (Grant No. BK2006088)     

The Characterization of Finite Simple Groups, L3（3^2m-1）（m≥2）, by Their Element Orders

In this paper the following theorem is proved： Every group L3（q） for q = 3^（2m-1）（m≥2） is characterized by its set of element orders.     

Finite groups in which elements of the same order outside the center are conjugate

We prove that if G is a finite group in which the elements of the same order outside the center are conjugate,then either G is abelian or G(?)S_3.     

Exact traveling wave solutions and dynamical behavior for the (<Emphasis Type="Italic">n</Emphasis> + 1)-dimensional multiple sine-Gordon equation

Using the methods of dynamical systems for the (n + 1)-dimensional multiple sine-Gordon equation, the existences of uncountably infinite many periodic wave solutions and breaking bounded wave solutions are obtained. For the double sine-Gordon equation, the exact explicit parametric representations of the bounded traveling solutions are given. To guarantee the existence of the above solutions, all parameter conditions are determined. This work was supported by the National Natural Science Foundation of China (Grant No. 11671179) and the Natural Science Foundation of Yunnan Province (Grant No. 2005A0092M).     

Two Kinds of Numbers and Their Applications

C. Radoux （J. Comput. Appl. Math., 115 （2000） 471-477） obtained a computational formula of Hankel determinants on some classical combinatorial sequences such as Catalan numbers and polynomials, Bell polynomials, Hermite polynomials, Derangement polynomials etc. From a pair of matrices this paper introduces two kinds of numbers. Using the first kind of numbers we give a unified treatment of Hankel determinants on those sequences, i.e., to consider a general representation of Hankel matrices on the first kind of numbers. It is interesting that the Hankel determinant of the first kind of numbers has a close relation that of the second kind of numbers.     

Equivalent conditions of complete convergence for independent weighted sums

For a very general weight function, the equivalent conditions of complete convergence for weighted sums of independent but not necessary identically distributed random variables are given. The previous situation of only sufficient results except for particular weight functions is changed. These results may help deduce many known ones and bring to light richer content. Project supported by the National Natural Science Foundation of China (Grant No. 19671078). the Natural Science Foundation of the Highter Education Department of Cuangdong Province and the National Science Foundation of the Education Commission of Jiangsu Province.     

Nonlinear Degenerate Parabolic Equation with Nonlinear Boundary Condition

In this paper, we obtain the necessary and sufficient conditions on the global existence of all positive （weak） solutions to a nonlinear degenerate parabolic equation with nonlinear boundary condition.