查询词典 nonlinear oscillations

Firstly, the author establish the functions of stability on the basis of the spline function method ,according to the theory of geometrical nonlinear and the theory of stability, educe the stability equation of structure based on variational principle, then carry through the flexuosity analysis of CFST arch.The big distortion geometrical nonlinear was considered by the stability equation,the author simplified the problem of geometrical nonlinear through ignored quadratic term and reserve the simple term, at last boiled down to solve the linear stability equation of eigenvalue .

利用样条函数方法、根据几何非线性变形理论和结构稳定性理论，先建立起结构稳定的泛函，再由变分原理导出结构的稳定方程，进行钢管混凝土拱屈曲分析；本文所建立的稳定方程考虑了几何非线性的大变形效应，通过忽略几何非线性的二次项，保留一次项，将几何非线性问题简化，最后归结为求解线性稳定问题的特征值稳定方程，建立了结构非线性静力稳定性问题的新算法及失稳类型判别准则。

Based on the modem FEM with the dynamic substructure method, itd dynamic equation is established with almost no limits to DOFs of the system, in which the left side is the first approach of the nonlinear system and the right side is the excitation and coupling nonlinear pseudo forces. The modal analysis method is used to get the eigen solution to the reduced linear homogeneous dynamic differential equation. When the system is excited by the harmonic excitation at the right side of the equation, the nonlinear dynamic response can be calculated by the numerical method to give quantitative analysis.

基于近代有限元和子结构模态综合法的动力学建模方法，获得非线性系统动力学微分方程，其自由度几乎没有限制，对左端首次近似齐次方程进行模态分析，选取对响应有贡献的部分本征对，同样对右端激励和非线性伪力作模态变换，得到减缩后非线性系统耦合动力学微分方程。

In chapter two,We present a globally nonlinear implicit difference scheme,i.e., a nonlinear iterative algorithma has to be used to solve the system of the nonlinear algebraic equation at each discrete time step.

第二章构造了一个非线性隐差分格式，在每一个时间层上需要迭代求解非线性方程组，该格式可以保证离散电荷和离散能守恒。

By introducing the parameter , construct a new kind of weighted implicit difference scheme for (1+1)-dimension nonlinear Sine-Gordon equation and the generalized nonlinear Sine-Gordon equation respectively. Give out an ADI scheme for (2+1)-dimension nonlinear Sine-Gordon equation.

通过引进参数，分别为（1+1）维的非线性Sine-Gordon方程和广义的非线性Sine-Gordon方程建立了它们的加权隐式差分格式，给出了（2+1）维的非线性Sine-Gordon方程的ADI格式。

Presents the design of longitudinal control for ASTOVL lift-fan aircraft, a multi-variable, strong-coupling, complicated nonlinear system to make the system nonlinear offset and decouple, and the method used for linear system in designing the system to gain expectant flying qualities and the combination of aerodynamic control surfaces with thrust vectors to delay the control surfaces getting into saturation, and the minimum N-norm generalized inverse theorem of weighted generalized inverse adopted to apportion the moments commands, which make the control surfaces gain appropriate deflection and the simulation results to verify the dynamic inverse control laws designed really make the system nonlinear offset and decouple; when one command is given, only this output will response, and others do not response; when all commands are given together, the responses will be just the linear superpose of the response of each command, therefore the operation of the pilot will be simplified greatly.

摘 要： ASTOVL升力风扇飞机是多变量、强耦合、复杂的非线性系统，采用非线性动态逆理论设计控制律以实现系统的非线性对消及解耦，然后，采用线性系统的设计方法对系统进行设计，以使系统获得期望的飞行品质。同时，考虑到ASTOVL升力风扇飞机是由气动舵面和推力矢量融合作用的，为了延缓各舵面进入饱和的时间，采用加权广义逆中的极小N-范数广义逆定理分配力矩指令，从而使各舵面达到适当的偏转角。并将所设计的控制律进行了仿真，结果验证了所设计的动态逆控制律使系统实现了非线性对消和解耦，单个指令作用时，只有该项响应，其余不受影响；所有指令作用时，其结果就等于单个指令作用时的线性叠加，这样使驾驶员的操纵大大简化而易于控制，从而大大降低了飞行事故率。

At first, this paper surveys nonlinear control and the applications of neural networks in control respectively. Then it studies definitions, mathematical descriptions and conditions of invertibility for nonlinear systems, which are used to analyze the feasibility of inverse system control method. Conclusions about the feasibility of inverse control and the realizability of αth-order inverse systems in engineering are achieved. Furthermore, this paper discusses the feasibility, structure and identification of neural network αth-order inverse system for general single-input single-output continuous or discrete nonlinear systems and various composite control methods based on the αth-order inverse. At last, as a part work of an actual project, this paper focuses on the design of neural network αth-order inverse control method for thyristor controlled series compensation in power systems and its effect in improving the stability of power systems.

本文首先分别概述非线性系统的控制与人工神经网络在控制中的应用；然后研究非线性系统各种可逆性的定义、数学描述及可逆性条件，并用于分析逆系统控制方法的可行性，得出有关逆系统控制方法可行性的结论，阐明一般情况下α阶逆系统才工程可实现；接着本文针对一般单输入单输出连续、离散非线性系统，研究神经网络α阶逆系统的可行性、结构与辨识以及基于神经网络α阶逆系统的各种复合控制方法，并给出应用例子；最后本文结合实际项目，针对采用可控串补的电力系统，设计神经网络α阶逆系统控制方法，研究其对提高电力系统稳定性的作用。

Base vectors are selected for formulating the nonlinear mapping. An approximate explicit expression is formed by using the Nystrm method for nonlinear mapping which is not available originally. The data in the nonlinear input space is mapped into some linear feature subspace and fisher linear discriminant analysis is computed for the mapped data.

首先提取基向量；然后采用Nystrm方法，以基向量为训练样本，将形式未知的非线性映射近似表达为已知形式的非线性映射，这种近似的非线性映射将变量由非线性的输入空间转换到线性的特征子空间；最后对映射数据进行线性Fisher判别分析。

The theory of maximal monotone operator is one of the most importance successes in the area of nonlinear analysis. It provides a powerful general framework for the study of nonlinear partial differential equations, nonlinear integral equations, control theory, optimization. Practically, it has be applied abroad in physics, economics and engineering.

极大单调算子理论是非线性分析领域的有效工具之一，已被广泛应用于非线性偏微分方程、非线性积分方程、控制论、最优化理论等学科，在物理学、经济学、工程学等应用学科也有着广泛的应用。

Nonlinear functional analysis has become an important direction of research in modern mathematics,nonlinear operator theory is also an important part of nonlinear functional analysis.

非线性泛函分析已成为现代数学中的重要研究方向之一，而非线性算子理论又是非线性泛函分析的重要内容。

Nonlinear functional analysis is not only profound theory but also widelyused research discipline in mathematics, in the context of nonlinear problemsof mathematics and natural sciences, a number of theories and methods of dil-ing with nonlinear problems have been established.

非线性泛函分析是数学中既有深刻理论又有广泛应用的研究学科，以数学和自然科学中出现的非线性问题为背景，建立了处理非线性问题的若干理论和方法。

Liapunov—Schmidt method is one of the most important method in the bifurcation theory.

Liapunov—Schmidt方法是分叉理论的最重要方法之一。

Be courteous -- even when people are most discourteous to you .

要有礼貌──即使当別人对你最不礼貌的时候。