随机Gilpin-Ayala互惠模型研究

采用M-矩阵及Liapunov函数等方法,研究了随机Gilpin-Ayala互惠模型解的稳定性,并给出若干随机Gilpin-Ayala互惠模型的正平衡解稳定的充分条件.同时修正了文献-《Stability of Stochastic Gilpin-Ayala competition Models》的若干错误.     

基于亚正定阵的Volterra系统稳定性的若干新判据

将亚正定阵引入到V o lterra系统,获得了判定该系统在正的平衡态全局稳定、扇形稳定及关联稳定的另一些新方法.从应用情况看,本文方法是有效的而且更为实用.     

具有分布时滞和非局部空间效应的Gilpin-Ayala竞争模型的稳定性

本文构造并研究了一类具有分布时滞和非局部空间效应影响的Gilpin-Ayala竞争系统的反应扩散模型.利用线性稳定化方法和Redlinger上下解方法得到了该竞争模型的动力学性态,并证明了模型在边界平衡点和共存平衡点是全局渐近稳定的.     

关于非线性系统的非常稳定性及其应用

本文将C.V.Pao研究Liapunov稳定性的内积法改进、推广和发展,研究了非线性系统的非常稳定性、平衡位置的存在唯一性和Liapunov稳定性.将主要结果直接应用到非线性周期系统的稳态振荡的判定.     

一类含时滞的比率依赖捕食系统正平衡点的全局稳定性分析

讨论了一种食饵增长为Gilpin-Ayala型的比率依赖的食饵捕食者模型,利用第二加性复合矩阵原理证明线性化系统正轨道解的稳定性,结合系统在凸集中存在唯一的局部正平衡点,证明了正平衡点的全局渐近稳定性.结合数值模拟验证了所得结论的合理性,同时指出定理结论仅为充分条件,丰富完善了模型的动力学性质.     

含Grushin算子的加权椭圆系统稳定解的Liouville定理

考虑含Grushin算子的加权椭圆系统正稳定解的Liouville定理.首先建立这类椭圆系统稳定解的均值形式的判定准则,再建立新的比较原则,联合积分估计和Bootstrap迭代方法建立了权数指数不相等和指数为超临界时椭圆系统正稳定解的Liouville定理.     

生态系统中心焦点判定的新方法

给出在生态系统的研究中 ,中心焦点判定的一种新方法 .利用这种方法对一类生物化学反应模型进行了中心焦点的判定 ,从而比较完整地对相应的系统作了研究 .     

基于虚拟完整约束的欠驱动起重机控制方法

欠驱动系统的控制是非线性控制的一个重要领域,欠驱动系统指系统控制输入个数小于自由度个数的非线性系统.目前,欠驱动非线性系统动力学和控制研究的主要方法包括线性二次型最优控制方法和部分反馈线性化方法等,如何使系统持续的稳定在平衡位置一直是研究的难点.虚拟约束方法是指通过选择一个周期循环变化的变量作为自变量来设计系统的周期运动.该文以典型的欠驱动模型起重机为例,采用虚拟约束方法,使系统能够在平衡位置稳定或周期振荡运动.首先,通过建立虚拟约束,减少系统自由度变量;然后,通过部分反馈线性化理论推导出系统的状态方程;最后,通过线性二次调节器设计反馈控制器.仿真结果表明,重物在反馈控制下可以在竖直位置的附近达到稳定状态,反映了虚拟约束方法对欠驱动系统的有效性.     

一个环境数学模型的一致持久性与稳定性

本文研究一个生态环境数学模型当系统存在正平衡态时,通过利用Hale-Waltman关于一致持久的定理,得到了系统的一致持久性.也证明了当caμ相似文献   

一类具有脉冲效应的非线性竞争系统的持久及全局吸引性(英文)

通过利用常微分方程比较定理以及构造恰当Lyapounov泛函,研究了一类具有脉冲效应的广义非自治n种群Gilpin-Ayala竞争系统,给出了使系统正解持久以及全局吸引的充分性条件,所得结论改进并推广了一些现有结果.     

随机Gilpin-Ayala竞争模型的稳定性

本文主要研究了一类随机Gilpin—Ayala竞争模型，它比经典Lotka—Volterra竞争模型更具一般性和实际意义．通过应用M矩阵的性质，得出随机Gilpin—Ayala竞争模型的稳定性的一些结论。     

On Stability of Symplectic Algorithms

1.FundamentalDeflnitionsLemma1.Thesolutionofalinearoofinarydtherentialequationwithcon8tantcoeffcientY=AYissta6leifalleigenvalue8ofAhaven0nP6sitivercalpartsandtheeigenvalueswithnullrealpartaresingleroots0ftheminimalp0lynomial.,/P\ThelinearHamiltoniansystemcanbeden0tedasZ=JSZwhereZ=(q),J=(ELs),andtheHamiltonianfuncti0nH(z)=ty.Lemma2.Thesolution80flinearHamiltoniansy8temsarecmticallysta6leifalleigenvaluesofJShavenullrsalpartandaresinglerootsojtheminitnalp0lyno?nial.Definiti0n1.Whenthemo…     

Asymptotic behaviour of the stochastic Gilpin-Ayala competition models

In this paper, we investigate a stochastic Gilpin-Ayala competition system, which is more general and more realistic than the classical Lotka-Volterra competition system.We discuss the asymptotic behaviour in detail of the stochastic Gilpin-Ayala competition system, and comparing the classical Lotka-Volterra with Gilpin-Ayala competition system, we find that the latter has better properties.     

A new family of three-stage two-step P-stable multiderivative methods with vanished phase-lag and some of its derivatives for the numerical solution of radial Schrödinger equation and IVPs with oscillating solutions

A new family of three-stage two-step methods are presented in this paper. These methods are of algebraic order 12 and have an important P-stability property. To make these methods, vanishing phase-lag and some of its derivatives have been used. The main structure of these methods are multiderivative, and the combined phases have been applied for expanding stability interval and for achieving P-stability. The advantage of the new methods in comparison with similar methods, in terms of efficiency, accuracy, and stability, has been showed by the implementation of them in some important problems, including the radial time-independent Schrödinger equation during the resonance problems with the use of the Woods-Saxon potential, undamped Duffing equation, etc.

     

Weak Nonlinear Stability of Implicit Runge-Kutta Methods

Two slightly different test problems have been used to examinenonlinear stability behaviour of numerical methods for solvingsystems of ordinary differential equations. These test problems,for BN-stability and for monotonicity, both lead to the conceptof algebraic stability. In this paper, it is shown that thesetwo problems may be combined to yield weaker stability conditions.Nonautonomous systems give a more restrictive stability conditionthan autonomous systems. Irreducible methods with some zeroquadrature weights can be stable in this weak sense.     

双对角占优与非奇M-矩阵的判定

本文利用矩阵B=A A^T的双对角占优性给出了矩阵A为M矩阵的新判定准则，推广了已有的判定定理。实例说明，采用本文定理可以较为容易地得出判定结果，本文给出的判定准则具有简单、方便的特点，与已有的判定准则相比，具有更为广泛的适用范围。     

SERK2v2: A new second‐order stabilized explicit Runge‐Kutta method for stiff problems

Traditionally, explicit numerical algorithms have not been used with stiff ordinary differential equations (ODEs) due to their stability. Implicit schemes are usually very expensive when used to solve systems of ODEs with very large dimension. Stabilized Runge‐Kutta methods (also called Runge–Kutta–Chebyshev methods) were proposed to try to avoid these difficulties. The Runge–Kutta methods are explicit methods with extended stability domains, usually along the negative real axis. They can easily be applied to large problem classes with low memory demand, they do not require algebra routines or the solution of large and complicated systems of nonlinear equations, and they are especially suited for discretizations using the method of lines of two and three dimensional parabolic partial differential equations. In Martín‐Vaquero and Janssen [Comput Phys Commun 180 (2009), 1802–1810], we showed that previous codes based on stabilized Runge–Kutta algorithms have some difficulties in solving problems with very large eigenvalues and we derived a new code, SERK2, based on sixth‐order polynomials. Here, we develop a new method based on second‐order polynomials with up to 250 stages and good stability properties. These methods are efficient numerical integrators of very stiff ODEs. Numerical experiments with both smooth and nonsmooth data support the efficiency and accuracy of the new algorithms when compared to other well‐known second‐order methods such as RKC and ROCK2. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013