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连续型粒子群优化算法的均方收敛性分析 被引量:10
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作者 罗金炎 《电子学报》 EI CAS CSCD 北大核心 2012年第7期1364-1367,共4页
粒子群优化算法是基于生物群体内个体间的合作与竞争等复杂行为产生的群体智能优化算法,已有的理论分析多在确定性的情况下进行算法收敛性分析.本文基于随机系统的矩方程法分析了连续型粒子群优化算法的均方收敛性,并给出了能够保证算... 粒子群优化算法是基于生物群体内个体间的合作与竞争等复杂行为产生的群体智能优化算法,已有的理论分析多在确定性的情况下进行算法收敛性分析.本文基于随机系统的矩方程法分析了连续型粒子群优化算法的均方收敛性,并给出了能够保证算法均方收敛域,最后通过仿真实验分析验证了相关结论. 展开更多
关键词 矩方程法 随机过程 粒子群优化算法 均方收敛
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三维副翼铰链力矩计算 被引量:10
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作者 吴宗成 朱自强 +1 位作者 丁宁 陈泽民 《航空学报》 EI CAS CSCD 北大核心 2007年第3期519-526,共8页
数值模拟了带副翼偏转构型的二维、三维亚、跨、超声速来流情况的绕流流场,采用有限体积方法和AUSM+迎风格式数值求解N-S方程,四步龙格-库塔时间推进,湍流模型为Baldwin-Lomax和Spalart-All-maras湍流模型。二维模拟压强分布与实验数据... 数值模拟了带副翼偏转构型的二维、三维亚、跨、超声速来流情况的绕流流场,采用有限体积方法和AUSM+迎风格式数值求解N-S方程,四步龙格-库塔时间推进,湍流模型为Baldwin-Lomax和Spalart-All-maras湍流模型。二维模拟压强分布与实验数据以及CFD软件模拟结果吻合较好。采用交错对接网格,数值模拟了不同副翼偏角和缝隙、来流马赫数、迎角和雷诺数的三维构型流场。通过舵面铰链力矩与实验数据的对比分析表明了该数值方法模拟此类复杂流场的可靠性和舵面铰链力矩计算的有效性。发现并研究了亚声速来流时铰链力矩随迎角的反向变化趋势,初步分析了副翼的缝隙和雷诺数效应。 展开更多
关键词 副翼 铰链力矩 N-S方程
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稀薄气体动力学矩方法研究综述 被引量:7
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作者 陈伟芳 赵文文 +1 位作者 江中正 刘华林 《气体物理》 2016年第5期9-24,共16页
临近空间位于航天器入轨与返回的必经区域,也是临近空间高超声速飞行器长航时飞行空域,空间环境的特殊性决定了飞行器在穿越时必须考虑稀薄大气环境对飞行器气动力防隔热通讯及控制的影响.Boltzmann方程作为描述气体分子速度分布函数演... 临近空间位于航天器入轨与返回的必经区域,也是临近空间高超声速飞行器长航时飞行空域,空间环境的特殊性决定了飞行器在穿越时必须考虑稀薄大气环境对飞行器气动力防隔热通讯及控制的影响.Boltzmann方程作为描述气体分子速度分布函数演化规律的微分-积分形式,在一定条件下能够描述从自由分子流到连续流全流域流动现象.作为Boltzmann方程的宏观表达形式,矩方程这一经典流体力学方程形式涵盖了Euler方程N-S方程Burnett方程super-Burnett方程及近年来发展的广义流体力学方程——非线性本构关系模型等.由于成熟的CFD数值计算理论及有限矩方程较高的计算效率,滑移过渡流矩方法相比粒子仿真与Boltzmann模型方程方法具有十分显著的优势和巨大的工程应用潜力.因此,对近年来传统及新型矩方法研究所取得的进展进行归纳总结,并针对关键科学问题开展理论与数值计算方法研究,具有十分重要的理论与工程应用价值. 展开更多
关键词 BOLTZMANN方程 矩方法 稀薄气体动力学
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卷弧翼弹零攻角流场数值模拟 被引量:5
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作者 宋旭民 夏刚 +1 位作者 秦子增 寇保华 《战术导弹技术》 2002年第6期21-24,共4页
通过数值求解三维欧拉方程 ,模拟了一种卷弧形尾翼弹在零攻角下的超音速外流场 ,得到了弹的滚动力矩系数在马赫数 1.4~ 3.0的变化特性 ,与试验数据做了比较 ,并对不同马赫数下的流场做了对比分析 .
关键词 零攻角 卷弧翼弹 流场 滚动力矩 数值模拟 欧拉方程 卷弧形尾翼 导弹
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扭转陀螺的运动研究 被引量:5
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作者 洪子昕 时凯 艾清 《物理实验》 2018年第6期35-39,共5页
运用欧拉动力学方程分析了扭转陀螺的力学特性,从理论上预测了陀螺释放后250s内的运动情况,实验研究了陀螺的定轴性和进动性对陀螺运动的影响.实验结果表明:在初始扭转力矩变大时,进动角与章动角的角速度与角度峰值都会变大,但变化周期... 运用欧拉动力学方程分析了扭转陀螺的力学特性,从理论上预测了陀螺释放后250s内的运动情况,实验研究了陀螺的定轴性和进动性对陀螺运动的影响.实验结果表明:在初始扭转力矩变大时,进动角与章动角的角速度与角度峰值都会变大,但变化周期几乎不变. 展开更多
关键词 陀螺 扭转力矩 欧拉动力学方程
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ALMOST SURE AND MOMENT EXPONENTIAL STABILITY OF PREDICTOR-CORRECTOR METHODS FOR STOCHASTIC DIFFERENTIAL EQUATIONS 被引量:4
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作者 Yuanling NIU Chengjian ZHANG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2012年第4期736-743,共8页
This paper deals with almost sure and moment exponential stability of a class of predictor- corrector methods applied to the stochastic differential equations of Ito-type. Stability criteria for this type of methods a... This paper deals with almost sure and moment exponential stability of a class of predictor- corrector methods applied to the stochastic differential equations of Ito-type. Stability criteria for this type of methods are derived. The methods are shown to maintain almost sure and moment exponential stability for all sufficiently small timesteps under appropriate conditions. A numerical experiment further testifies these theoretical results. 展开更多
关键词 Almost sure stability moment exponential stability numerical experiment stochastic differential equations.
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Stability of a delayed predator prey model in a random environment 被引量:1
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作者 靳艳飞 谢文贤 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第11期140-145,共6页
The stability of the first-order and second-order solution moments for a Harrison-type predator-prey model with parametric Gaussian white noise is analyzed in this paper. The moment equations of the system solution ar... The stability of the first-order and second-order solution moments for a Harrison-type predator-prey model with parametric Gaussian white noise is analyzed in this paper. The moment equations of the system solution are obtained under Ito interpretations. The delay-independent stable condition of the first-order moment is identical to that of the deterministic delayed system, and the delay-independent stable condition of the second-order moment depends on the noise intensities. The corresponding critical time delays are determined once the stabilities of moments lose. Further, when the time delays are greater than the critical time delays, the system solution becomes unstable with the increase of noise intensities. Finally, some numerical simulations are given to verify the theoretical results. 展开更多
关键词 delay-independent stability predator-prey model moment equations environmental noise
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采用耦合Hallen方程分析八木天线 被引量:1
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作者 周波 邢锋 楼建东 《现代电子技术》 2008年第11期81-83,共3页
八木天线是一种常用的天线形式,采用了二元偶极子模型的耦合方程,并结合矩量法Hallen方程分域基分析了八木天线的数值计算方法。运用此方法,充分考虑了阵元间的互耦效应,而且计算起来比较简便,并降低了矩阵维数。仿真设计了一个三元八... 八木天线是一种常用的天线形式,采用了二元偶极子模型的耦合方程,并结合矩量法Hallen方程分域基分析了八木天线的数值计算方法。运用此方法,充分考虑了阵元间的互耦效应,而且计算起来比较简便,并降低了矩阵维数。仿真设计了一个三元八木天线,计算结果与传统方法比较,表明了此方法准确有效。 展开更多
关键词 互耦效应 八木天线 矩量法 Hallen方程
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Volterra Integral Equations and Some Nonlinear Integral Equations with Variable Limit of Integration as Generalized Moment Problems 被引量:1
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作者 Maria B. Pintarelli 《Journal of Mathematics and System Science》 2015年第1期32-38,共7页
In this paper we will see that, under certain conditions, the techniques of generalized moment problem will apply to numerically solve an Volterra integral equation of first kind or second kind. Volterra integral equa... In this paper we will see that, under certain conditions, the techniques of generalized moment problem will apply to numerically solve an Volterra integral equation of first kind or second kind. Volterra integral equation is transformed into a one-dimensional generalized moment problem, and shall apply the moment problem techniques to find a numerical approximation of the solution. Specifically you will see that solving the Volterra integral equation of first kind f(t) = {a^t K(t, s)x(s)ds a ≤ t ≤ b or solve the Volterra integral equation of the second kind x(t) =f(t)+{a^t K(t,s)x(s)ds a ≤ t ≤ b is equivalent to solving a generalized moment problem of the form un = {a^b gn(s)x(s)ds n = 0,1,2… This shall apply for to find the solution of an integrodifferential equation of the form x'(t) = f(t) + {a^t K(t,s)x(s)ds for a ≤ t ≤ b and x(a) = a0 Also considering the nonlinear integral equation: f(x)= {fa^x y(x-t)y(t)dt This integral equation is transformed a two-dimensional generalized moment problem. In all cases, we will find an approximated solution and bounds for the error of the estimated solution using the techniques ofgeneralized moment problem. 展开更多
关键词 Generalized moment problems solution stability Volterra integral equations nonlinear integral equations.
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Solution of Partial Derivative Equations of Poisson and Klein-Gordon with Neumann Conditions as a Generalized Problem of Two-Dimensional Moments
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作者 Maria B. Pintarelli 《Journal of Applied Mathematics and Physics》 2020年第8期1606-1614,共9页
It will be shown that finding solutions from the Poisson and Klein-Gordon equations under Neumann conditions are equivalent to solving an integral equation, which can be treated as a generalized two-dimensional moment... It will be shown that finding solutions from the Poisson and Klein-Gordon equations under Neumann conditions are equivalent to solving an integral equation, which can be treated as a generalized two-dimensional moment problem over a domain that is considered rectangular. The method consists to solve the integral equation numerically using the two-dimensional inverse moments problem techniques. We illustrate the different cases with examples. 展开更多
关键词 Equation in Poisson Partial Derivatives Klein-Gordon Equation Integral equations Generalized moment Problem
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Parabolic Partial Differential Equations with Border Conditions of Dirichlet as Inverse Moments Problem
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作者 Mara B. Pintarelli 《Applied Mathematics》 2017年第1期15-25,共11页
We considerer parabolic partial differential equations: under the conditions , on a region . We will see that an approximate solution can be found using the techniques of generalized inverse moments problem and also b... We considerer parabolic partial differential equations: under the conditions , on a region . We will see that an approximate solution can be found using the techniques of generalized inverse moments problem and also bounds for the error of estimated solution. First we transform the parabolic partial differential equation to the integral equation . Using the inverse moments problem techniques we obtain an approximate solution of . Then we find a numerical approximation of when solving the integral equation , because solving the previous integral equation is equivalent to solving the equation . 展开更多
关键词 PARABOLIC PDES Integral equations Generalized moment PROBLEM
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A Method of Moment Approach in Solving Boundary Value Problems
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作者 Hilal M. El Misilmani Karim Y. Kabalan +1 位作者 Mohamad Y. Abou-Shahine Mohammed Al-Husseini 《Journal of Electromagnetic Analysis and Applications》 2015年第3期61-65,共5页
Several available methods, known in literatures, are available for solving nth order differential equations and their complexities differ based on the accuracy of the solution. A successful method, known to researcher... Several available methods, known in literatures, are available for solving nth order differential equations and their complexities differ based on the accuracy of the solution. A successful method, known to researcher in the area of computational electromagnetic and called the Method of Moment (MoM) is found to have its way in this domain and can be used in solving boundary value problems where differential equations are resulting. A simplified version of this method is adopted in this paper to address this problem, and two differential equations examples are considered to clarify the approach and present the simplicity of the method. As illustrated in this paper, this approach can be introduced along with other methods, and can be considered as an attractive way to solve differential equations and other boundary value problems. 展开更多
关键词 Boundary Value Problem Differential equations METHOD of moment GALERKIN METHOD WEIGHT Coefficient
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Derivation of Moment Equations for the Theoretical Description of Electrons in Nonthermal Plasmas
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作者 Markus M. Becker Detlef Loffhagen 《Advances in Pure Mathematics》 2013年第3期343-352,共10页
The derivation of moment equations for the theoretical description of electrons is of interest for modelling of gas discharge plasmas and semiconductor devices. Usually, certain artificial closure assumptions are appl... The derivation of moment equations for the theoretical description of electrons is of interest for modelling of gas discharge plasmas and semiconductor devices. Usually, certain artificial closure assumptions are applied in order to derive a closed system of moment equations from the electron Boltzmann equation. Here, a novel four-moment model for the description of electrons in nonthermal plasmas is derived by an expansion of the electron velocity distribution function in Legendre polynomials. The proposed system of partial differential equations is consistently closed by definition of transport coefficients that are determined by solving the electron Boltzmann equation and are then used in the fluid calculations as function of the mean electron energy. It is shown that the four-moment model can be simplified to a new drift-diffusion approximation for electrons without loss of accuracy, if the characteristic frequency of the electric field alteration in the discharge is small in comparison with the momentum dissipation frequency of the electrons. Results obtained by the proposed fluid models are compared to those of a conventional drift-diffusion approximation as well as to kinetic results using the example of low pressure argon plasmas. It is shown that the results provided by the new approaches are in good agreement with kinetic results and strongly improve the accuracy of fluid descriptions of gas discharges. 展开更多
关键词 moment equations PLASMA Modelling ELECTRON Transport
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Moment Equations of Linear It Stochastic Systems with Applications
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作者 Deng Feiqi Liu Hongwei Feng Zhaoshu & Liu Yongqing(Department of Automatic Control Engineering, South China University of Technology,Guangzhou 510641, P. R. China) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1998年第2期1-7,共7页
In this paper, with the Kronecker's product and Kronecker's sum of matrices, the 2nd order moment equations of linear Ito stochastic systems are dervided. Based on the moment equations obtained, a necessary an... In this paper, with the Kronecker's product and Kronecker's sum of matrices, the 2nd order moment equations of linear Ito stochastic systems are dervided. Based on the moment equations obtained, a necessary and sufficient condition for the mean-square asymptotic stability of linear Ito stochastic systems is obtained.For the time-invariant stochastic systems,the necessary and sufficient condition is just the same as the Hurwitz property of certain matrices related to the coefficient matrices of the systems. An algorithm STILSS is given for testing the mean-square asymptotic stability of time-invariant linear Ito stochastic systems. 展开更多
关键词 moment equations Mean-square stability Necessary and sufficient condition ALGORITHM
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Asymptotical p-Moment Stability of Stochastic Impulsive Differential Equations and Its Application in Impulsive Control 被引量:1
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作者 牛玉俊 徐伟 李红武 《Communications in Theoretical Physics》 SCIE CAS CSCD 2010年第1期110-114,共5页
In this paper, the asymptotical p-moment stabifity of stochastic impulsive differential equations is studied, and a comparison theory to ensure the asymptotieal p-moment stability for trivial solution of this system i... In this paper, the asymptotical p-moment stabifity of stochastic impulsive differential equations is studied, and a comparison theory to ensure the asymptotieal p-moment stability for trivial solution of this system is established, from which we can find out whether a stochastic impulsive differential system is stable just from a deterministic comparison system. As an application of this theory, we control the chaos of stochastic Chen system using impulsive method, and a stable region is deduced too. Finally, numerical simulations verify the feasibility of our method. 展开更多
关键词 p-moment stability IMPULSIVE WHITE-NOISE stochastic differential equations
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非Gauss分布随机波浪力对海洋平台的非线性作用 被引量:1
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作者 祁德庆 王天竹 乐嘉春 《力学季刊》 CSCD 北大核心 2005年第2期276-279,共4页
为避免求解决定Markov过程转移概率密度的Fokker-Planck方程,基于尺度分离的假设导出了一组描述非线性海洋平台受非Gauss分布随机波浪载荷作用所产生响应的矩量的常微分方程组。矩量方程清楚地反映出分别对应随机载荷和结构响应的两种... 为避免求解决定Markov过程转移概率密度的Fokker-Planck方程,基于尺度分离的假设导出了一组描述非线性海洋平台受非Gauss分布随机波浪载荷作用所产生响应的矩量的常微分方程组。矩量方程清楚地反映出分别对应随机载荷和结构响应的两种不同统计特性的相互关系。由于矩量方程不依赖载荷的概率分布的具体细节,以它来模拟随机激励作用下的非线性系统将免于MonteCarlo方法所面临的正确模拟载荷概率分布的困难任务。将摄动法用于矩量方程可使线性化不再需要,这样就不会因为线性化而产生不可预料的误差。 展开更多
关键词 非Gauss分布白噪声 随机微分方程 非线性系统 矩量方程
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明渠水流泥沙运动水深平均及力矩方程的理论和验证 被引量:1
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作者 郭庆超 Yee-Chung Jin 郑勇 《泥沙研究》 CSCD 北大核心 2002年第5期15-24,共10页
首次提出了水流泥沙运动水深平均及其力矩方程的概念 ,并从理论上推导出这套方程组。提出水流泥沙运动力矩方程的目的有两个 ,一是在不增加空间维数的情况下可以有效地恢复水流泥沙因子沿水深分布信息 ,克服目前普遍使用的水深平均方程... 首次提出了水流泥沙运动水深平均及其力矩方程的概念 ,并从理论上推导出这套方程组。提出水流泥沙运动力矩方程的目的有两个 ,一是在不增加空间维数的情况下可以有效地恢复水流泥沙因子沿水深分布信息 ,克服目前普遍使用的水深平均方程过多地忽略沿水深分布信息的缺点 ;二是增强模型的模拟能力。针对这两个目的是否能真正得到体现 ,分别从理论和实验室资料两个方面对新推导的力矩方程进行了全面的检验。理论验证结果表明 ,一维的力矩方程除了能模拟水深平均的流速和含沙量 ,还能够较好地模拟水流泥沙因子沿水深分布信息 ,这充分说明了一维力矩方程的二维特性。为了检验力矩方程的模拟能力 ,特别选取了一些极端的水流泥沙运动实验 ,如清水冲刷、点源加沙和深槽回淤等。模拟结果表明 。 展开更多
关键词 明渠 泥沙运动 力矩方程 清水冲刷 点源加沙 深槽回淤
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Laplace-Transform Finite Element Solution of Nonlocal and Localized Stochastic Moment Equations of Transport 被引量:1
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作者 Eric Morales-Casique Shlomo P.Neuman 《Communications in Computational Physics》 SCIE 2009年第6期131-161,共31页
Morales-Casique et al.(Adv.Water Res.,29(2006),pp.1238-1255)developed exact first and second nonlocal moment equations for advective-dispersive transport in finite,randomly heterogeneous geologic media.The velocity an... Morales-Casique et al.(Adv.Water Res.,29(2006),pp.1238-1255)developed exact first and second nonlocal moment equations for advective-dispersive transport in finite,randomly heterogeneous geologic media.The velocity and concentration in these equations are generally nonstationary due to trends in heterogeneity,conditioning on site data and the influence of forcing terms.Morales-Casique et al.(Adv.Water Res.,29(2006),pp.1399-1418)solved the Laplace transformed versions of these equations recursively to second order in the standard deviationσY of(natural)log hydraulic conductivity,and iteratively to higher-order,by finite elements followed by numerical inversion of the Laplace transform.They did the same for a space-localized version of the mean transport equation.Here we recount briefly their theory and algorithms;compare the numerical performance of the Laplace-transform finite element scheme with that of a high-accuracy ULTIMATE-QUICKEST algorithm coupled with an alternating split operator approach;and review some computational results due to Morales-Casique et al.(Adv.Water Res.,29(2006),pp.1399-1418)to shed light on the accuracy and computational efficiency of their recursive and iterative solutions in comparison to conditional Monte Carlo simulations in two spatial dimensions. 展开更多
关键词 Geologic media porous media random heterogeneity CONDITIONING stochastic transport moment equations NONLOCALITY localization Laplace transform finite elements ultimatequickest
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一类随机Harrison型捕食与被捕食系统的稳定性分析 被引量:1
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作者 牛嗣永 靳艳飞 《动力学与控制学报》 2016年第3期276-282,共7页
研究了一种具有Harrison功能反应函数的随机捕食与被捕食系统模型,该模型中捕食者的死亡率和被捕食者的增长率受到独立同分布的两对称三值噪声的影响.文中运用线性化理论和Shapiro-Loginov方程给出了系统扰动的一阶矩和二阶矩方程,并用R... 研究了一种具有Harrison功能反应函数的随机捕食与被捕食系统模型,该模型中捕食者的死亡率和被捕食者的增长率受到独立同分布的两对称三值噪声的影响.文中运用线性化理论和Shapiro-Loginov方程给出了系统扰动的一阶矩和二阶矩方程,并用Routh-Hurwitz稳定性判据给出了系统稳定的条件.研究表明噪声强度σ和噪声自相关时间τ均对系统的稳定性有影响.当噪声强度充分大或噪声自相关时间足够小都能使系统失稳.最后通过数值方法,验证了分析结果的准确性. 展开更多
关键词 三值噪声 Harrison捕食与被捕食系统 稳定性 矩方程 Shapiro-Loginov方程
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ASYMPTOTICS OF THE SOLUTIONS TO STOCHASTIC WAVE EQUATIONS DRIVEN BY A NON-GAUSSIAN LéVY PROCESS
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作者 Yiming JIANG Suxin WANG Xingchun WANG 《Acta Mathematica Scientia》 SCIE CSCD 2019年第3期731-746,共16页
In this article, we consider the long time behavior of the solutions to stochastic wave equations driven by a non-Gaussian Lévy process. We shall prove that under some appropriate conditions, the exponential stab... In this article, we consider the long time behavior of the solutions to stochastic wave equations driven by a non-Gaussian Lévy process. We shall prove that under some appropriate conditions, the exponential stability of the solutions holds. Finally, we give two examples to illustrate our results. 展开更多
关键词 Stochastic wave equations non-Gaussian Lévy processes exponential stability second moment stability
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