单向分类随机效应模型中方差分量的渐近最优经验Bayes估计

本文在加权平方损失下导出了单向分类随机效应模型中方差分量的Bayes估计, 利用多元密度及其偏导数的核估计方法构造了方差分量的经验Bayes(EB)估计,证明了 EB估计的渐近最优性.文末还给出了一个例子说明了符合定理条件的先验分布是存在 的.     

相依样本下概率密度函数估计的渐近正态

设随机变量 X具有概率密度函数 f (x) ,X1,… ,Xn为 f (x)的样本 ,基于 X1,… ,Xn定义一类 f (x)的估计 fn(x) .本文在 X1,… ,Xn为 α——混合、ρ——混合样本时 ,得到了 fn(x)的渐近正态性     

Dynamics of an SI epidemic model with external effects in a polluted environment

In a polluted environment, considering the biological population infected with some kinds of diseases and hunted by human beings, we formulate two SI pollution-epidemic models with continuous and impulsive external effects, respectively, and investigate the dynamics of such systems. We assume that only the susceptible population is hunted by human beings. For the continuous system, we obtain sufficient conditions of the ultimate boundedness of solutions and the global asymptotical stability of equilibria. For the impulsive system, by using the comparison theorem and the analysis method, we show that under different conditions the disease-free periodic solution is globally asymptotically attractive, or the system is permanent. Numerical simulations confirm our theoretical results.     

Persistence,extinction and global asymptotical stability of a non-autonomous predator–prey model with random perturbation

A two-species stochastic non-autonomous predator–prey model is investigated. Sufficient criteria for extinction, non-persistence in the mean and weak persistence in the mean are established. The critical value between persistence and extinction is obtained for each species in many cases. It is also shown that the system is globally asymptotically stable under some simple conditions. Some numerical simulations are introduced to illustrate the main results.     

Static flow on complete noncompact manifolds I: short-time existence and asymptotic expansions at conformal infinity

We study short-time existence of static flow on complete noncompact asymptotically static manifolds from the point of view that the stationary points of the evolution equations can be interpreted as static solutions of the Einstein vacuum equations with negative cosmological constant.For a static vacuum(Mn,g,V),we also compute the asymptotic expansions of g and V at conformal infinity.     

On Belinskii conformality in countable sets of points

The local behavior of plane quasiconformal mappings is investigated. In particular, generalizing the well-known Reich-Walczak problem, we study the possibility for a quasiconformal mapping to be conformal in the sense of Belinskii at a prescribed point or in a prescribed set of points when the modulus of the complex dilatation is a fixed measurable function. The notion of the Belinskii conformality is related to the conception of asymptotical rotations by Brakalova and Jenkins.

     

GLOBAL STABILITY IN TIME-DELAYED 3-DIMENSIONAL RICHARDS MODEL

We obtain the global attractivity and global asymptotical stability of positive equilibria to a 3-dimensional Richards model with delays. Our results do not depend on the size-asymmetry parameter which measures the degree of the curvature of size-growth among individuals over the entire growth curve, and the shape parameter which affects the shape of model curve. Lastly, we gave a numerical simulation to verify the feasibility of our main results.     

Asymptotical Stability of Numerical Methods with Constant Stepsize for Pantograph Equations

In this paper, the asymptotical stability of the analytic solution and the numerical methods with constant stepsize for pantograph equations is investigated using the Razumikhin technique. In particular, the linear pantograph equations with constant coefficients and variable coefficients are considered. The stability conditions of the analytic solutions of those equations and the numerical solutions of the θ-methods with constant stepsize are obtained. As a result Z. Jackiewicz’s conjecture is partially proved. Finally, some experiments are given. AMS subject classification (2000) 65L02, 65L05, 65L20     

一类四阶非线性系统的全局渐近稳定性

运用类比法,构造了一类四阶非线性系统的李雅普诺夫函数,得到其平凡解全局渐近稳定的充分性准则,推广并改进了有关这类系统的其它结果.     

Global asymptotical properties for a diffused HBV infection model with CTL immune response and nonlinear incidence

This article proposes a diffused hepatitis B virus (HBV) model with CTL immune response and nonlinear incidence for the control of viral infections. By means of different Lyapunov functions, the global asymptotical properties of the viral-free equilibrium and immune-free equilibrium of the model are obtained. Global stability of the positive equilibrium of the model is also considered. The results show that the free diffusion of the virus has no effect on the global stability of such HBV infection problem with Neumann homogeneous boundary conditions.