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将Euler(欧拉)角表示引入转子动力学系统,用以描述转子的非线性旋转运动,并与时间有限元相结合,进而提出了包含非线性因素的转子动力学保辛数值求解方法.以此方法为基础,分析了悬臂梁-圆盘转子系统的涡动行为.数值结果证明该数值解法的有效性与正确性,可用于各种转子系统涡动行为分析. 相似文献
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研究了转子-密封系统在气流激振力作用下的低频振动——1∶2亚谐共振现象.利用流体计算动力学(CFD)方法对转子-密封系统进行了流场模拟计算,辨识出适用于气流流场的Muszynska模型参数,并建立了转子-密封系统动力学方程.采用多尺度方法将系统进行3次截断,并得到系统响应.采用奇异性理论研究了系统的1∶2亚谐共振,进一步得到系统亚谐共振的分岔方程和转迁集,根据转迁集给出了在不同奇异性参数空间内的分岔图.同时,由分岔方程得到了亚谐共振非零解存在的条件.其分析结果对抑制转子-密封系统的亚谐振动有重要的工程意义. 相似文献
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针对等式约束非线性最优控制问题,通过一阶Taylor级数展开,得到线性化的动力学方程,进而在方程原变量的基础上,引入对偶向量(Lagrange乘子向量),将动力学方程从Lagrange体系引入到了Hamilton体系,在全状态下,从一个新的角度对等式约束非线性控制问题进行了描述,进一步基于时程精细积分理论,对其方程进行了有效的精细求解,并通过算例说明了文中方法的有效性。 相似文献
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郝兴文 《数学年刊A辑(中文版)》2014,35(6):661-674
非自治退化抛物-双曲型方程可以描述许多自然现象.主要研究这类方程的柯西问题,建立了动力学公式,在对流函数、扩散函数适当光滑性的基础上,证明了该问题动力学解的存在唯一性. 相似文献
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将四元数引入多体动力学系统,用以描述刚体转动分量,继而据此将问题转入约束动力学领域,建立相关的Lagrange体系.然后引入作用量并进行有限元近似,并保证格点上严格满足约束条件,则根据分析结构力学基本理论,可导出逐步积分的递推格式,并且积分保辛.该法具有未知数少、计算量小等优点,数值结果令人满意. 相似文献
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对于反应动力学而言,尽管常微分方程已经成为了基本的研究工具,仍然无法精确描述离散分子的随机演变规律.化学Langevin方程的出现则打破了这个困境,使得研究者从随机角度进行动力学数值模拟成为可能.这种模拟可以为研究提供基本的动力学信息.建立了探测刚性并剖分系统为不同时间尺度子系统的自适应策略,并构建了基于算子分裂的多时间尺度反应体系的随机模拟方法.方法运用于两种基本的酶动力反应体系的模拟实验结果表明,随机分裂方法对于具有清晰时间差异的刚性系统能够实现高效且精确模拟,并且保持了反应体系的动力特性. 相似文献
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本文建立了多体机械手的一般动力学方程.设多体系统是由任意数目的刚体组成的树形拓扑结构,并认为铰是柱铰链,允许具有相对转动和滑动.考虑到实际问题中摩擦力的影响,采用Newton-Euler方法,建立了运动方程.进一步通过构造分配矩阵,将动力学方程分离,得到了一组实用的力方程和运动方程. 相似文献
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Zdenka Rendlova 《PAMM》2011,11(1):65-66
This paper aims at creating a mathematical model of a bending oscillation rotor system which enables to execute a dynamical analysis of its vibration including the influence of nonlinear bearing characteristics. More specifically, using the finite element method the model of rotating system supported by four hydrodynamic bearings was created. The basic dynamical analysis of the rotor system was performed and the eigenvalues, eigenvectors and stability conditions were evaluated. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Anwar Ja’afar Mohamad-JawadMarko D. Petkovi? Anjan Biswas 《Applied mathematics and computation》2011,217(16):7039-7047
This paper applies the variational iteration method (VIM) and semi-inverse variational principle to obtain solutions of linear and nonlinear partial differential equations. The nonlinear model is considered from gas dynamics, fluid dynamics and Burgers equation. The linear model is the heat transfer (diffusion) equation. Results show that variational iteration method is a powerful mathematical tool for solving linear and nonlinear partial differential equations, and therefore, can be widely applied to engineering problems. 相似文献
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A mathematical model incorporating the higher order deformations in bending is developed and analyzed to investigate the nonlinear dynamics of rotors. The rotor system considered for the present work consists of a flexible shaft and a rigid disk. The shaft is modeled as a beam with a circular cross section and the Euler Bernoulli beam theory is applied with added effects such as rotary inertia, gyroscopic effect, higher order large deformations, rotor mass unbalance and dynamic axial force. The kinetic and strain (deformation) energies of the rotor system are derived and the Rayleigh–Ritz method is used to discretize these energy expressions. Hamilton’s principle is then applied to obtain the mathematical model consisting of second order coupled nonlinear differential equations of motion. In order to solve these equations and hence obtain the nonlinear dynamic response of the rotor system, the method of multiple scales is applied. Furthermore, this response is examined for different possible resonant conditions and resonant curves are plotted and discussed. It is concluded that nonlinearity due to higher order deformations significantly affects the dynamic behavior of the rotor system leading to resonant hard spring type curves. It is also observed that variations in the values of different parameters like mass unbalance and shaft diameter greatly influence dynamic response. These influences are also presented graphically and discussed. 相似文献
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In this paper,we investigate the pseudo almost periodicity of the unique bounded solution for a nonlinear hyperbolic equation with piecewise constant argument.The equation under consideration is a mathematical model for the dynamics of gas absorption. 相似文献
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In this paper, we investigate the pseudo almost periodicity of the unique bounded solution for a nonlinear hyperbolic equation with piecewise constant argument. The equation under consideration is a mathematical model for the dynamics of gas absorption, 相似文献
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V. A. Rukavishnikov O. P. Tkachenko 《Computational Mathematics and Mathematical Physics》2008,48(1):139-146
A mathematical model of nonlinear wave propagation in a pipeline is constructed. The Korteweg-de Vries equation is derived by determining asymptotic solutions and changing variables. A particular solution to the model equations is found that has the fluid velocity function in the form of a solitary wave. Thus, the class of nonlinear fluid dynamics problems described by the KdV equation is expanded. 相似文献
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We consider the inverse problem for the quasilinear hyperbolic equation connected with the mathematical model of adsorption dynamics with a concentration-dependent kinetic coefficient. An iterative method is proposed that reduces the inverse problem to a nonlinear operator equation.__________Translated from Prikladnaya Matematika i Informatika, No. 17, pp. 5–12, 2004. 相似文献
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Slobodan Zdravković Louis Kavitha Miljko V. Satarić Slobodan Zeković Jovana Petrović 《Chaos, solitons, and fractals》2012,45(11):1378-1386
We here present a model of nonlinear dynamics of microtubules (MT) in the context of modified extended tanh-function (METHF) method. We rely on the ferroelectric model of MTs published earlier by Satari? et al. [1] where the motion of MT subunits is reduced to a single longitudinal degree of freedom per dimer. It is shown that such nonlinear model can lead to existence of kink solitons moving along the MTs. An analytical solution of the basic equation, describing MT dynamics, was compared with the numerical one and a perfect agreement was demonstrated. It is now clearer how the values of the basic parameters of the model, proportional to viscosity and internal electric field, impact MT dynamics. Finally, we offer a possible scenario of how living cells utilize these kinks as signaling tools for regulation of cellular traffic as well as MT depolymerisation. 相似文献
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《Mathematical and Computer Modelling》2007,45(3-4):340-354
The cycloidal gear drive is widely used in industrial applications, such as gerotor pump, speed reducer, transmission apparatus and so on. In this paper, the profile of inner rotor is with equidistance to an epitrochoidal (or extended epicycloid) curve, and the mathematical model of the internal cycloidal gear with tooth difference is created by the theory of gearing. The proposed mathematical model can simulate not only gerotor pump but also cycloidal speed reducer. The design of outer rotor depends on different applications. Being applied to the speed reducer, the outer rotor will be a pin wheel (outer rotor arc teeth). Besides, for a better design of the gerotor pump, the mathematical model of the generated shape between outer rotor arc teeth will also be proposed. Lastly, a simpler dimensionless equation of undercutting will be derived from the proposed mathematical model. And a more explicit procedure to determine the feasible design region without undercutting on the tooth profile or interference between the pins will be developed and demonstrated by some numerical examples. 相似文献
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This paper investigates the bifurcation and nonlinear behavior of an aerodynamic journal bearing system taking into account the effect of stationary herringbone grooves. A finite difference method based on the successive over relation approach is employed to solve the Reynolds’ equation. The analysis reveals a complex dynamical behavior comprising periodic and quasi-periodic responses of the rotor center. The dynamic behavior of the bearing system varies with changes in the bearing number and rotor mass. The results of this study provide a better understanding of the nonlinear dynamics of aerodynamic grooved journal bearing systems. 相似文献