基于周期分解的圆形分布法分析我国流行性乙型脑炎季节性特征

目的探讨基于周期分解的圆形分布法在分析我国乙脑季节特征方面应用的可行性,为乙脑的预防控制工作提供理论依据。方法以2011-2017年84个月的乙脑发病数据为基础,首先运用周期分解法分解出时间序列中的季节因素和长期趋势因素,得到季节指数,并对长期趋势进行拟合,然后构建基于季节性指数的圆形分布法并分析流行性乙型脑炎的季节性特征。结果 2011-2017年我国乙脑的长期趋势最佳模型为ARIMA(0,0,2)(R^2=0.829,平均相对误差MAPE=0.151),我国乙脑高峰期发病数呈逐年下降的趋势,发病流行期在6月至11月,高峰期在7月至9月,高发日在8月22日。结论满足圆形分布法的应用条件时,基于周期分解的圆形分布法在探讨乙脑季节特征方面具有较好的应用价值。

基于周期分解的圆形分布法分析我国流行性乙型脑炎季节特征

目的:探讨基于周期分解的圆形分布法在分析我国流行性乙型脑炎(乙脑)季节特征方面应用的可行性。方法:先使用周期分解法对我国2005年至2014年乙脑发病的季节特征进行分解,再用圆形分布法验证分解出来的季节指数的季节性特征。结果:2005年至2014年我国乙脑发病数呈下降的趋势;乙脑发病呈现出明显的季节性,发病高发日在8月16日,高峰期在7月至9月,流行期在6月至10月。结论:我国乙脑发病具有明显的季节性。满足圆形分布法的应用条件时,基于周期分解的圆形分布法在了解传染病季节特征方面具有较好的应用价值。

ON THE EXISTENCE OF PERIODIC SOLUTIONS FOR THE THIRD-ORDER NONLINEAR ORDINARY DIFFERENTIAL EQUATIONS

Abstract In this paper,the existence of periodic solution for the third order nonlinear ordinary differential equation of the form x…+f()+g()+h(x)=p(t) is considered,where f,g,h and p are the continuous functions,and p(t+T)=p(t). By using the Leray Schauder degree method,some sufficient conditions to guarantee the existence of T periodic solution for the equation are obtained.Some previous results are extended and improved.

Solitary Wave and Periodic Wave Solutions for the Relativistic Toda Lattices

In this work, an adaptation of the tanh/tan-method that is discussed usually in the nonlinear partial differential equations is presented to solve nonlinear polynomial differential-difference equations. As a concrete example,several solitary wave and periodic wave solutions for the chain which is related to the relativistic Toda lattice are derived.Some systems of the differential-difference equations that can be solved using our approach are listed and a discussion is given in conclusion.

A Computational Approach to the New Type Solutions of Whitham-Broer-KaupEquation in Shallow Water

Based on computerized symbolic computation,a new method and its algorithm are proposed for searching for exact travelling wave solutions of the nonlinear partial differential equations.Making use of our approach,we investigate the Whitham-Broer-Kaup equation in shallow water and obtain new families of exact solutions,which include soliton-like solutions and periodic solutions.As its special cases,the solutions of classical long wave equations and modified Boussinesq equations can also be found.

The Almost Periodic Solution on a Lienard Equation

By using exponential dichotomies and Liapunov function method, we have studied the existence of almost periodic solutions on a Lienard system and have obtained some simple sufficient condition.

New Doubly Periodic Solutions for the Coupled Nonlinear Klein-Gordon Equations

By using the general solutions of a new coupled Riccati equations, a direct algebraic method is described to construct doubly periodic solutions (Jacobi elliptic function solution) for the coupled nonlinear Klein-Gordon equations.It is shown that more doubly periodic solutions and the corresponding solitary wave solutions and trigonometric function solutions can be obtained in a unified way by this method.

Analytical Solution of Weak-Coupling Periodically Driven Two-Level System

We present an approximate analytical solution to periodically driven two-level system in the weak-coupling regime. The analytical solution is in good agreement with the exact numerical solution in resonance and near resonance cases when Ω 〈 0.3ωa with Ω and ωa denoting the Rabi and transition frequencies respectively.

ON PERIODIC DYNAMICAL SYSTEMS

The authors investigate the existence and the global stability of periodic solution for dynamical systems with periodic interconnections, inputs and self-inhibitions. The model is very general, the conditions are quite weak and the results obtained are universal.