THE BOUNDED EXTERMINATION AND STABILITY OF MUTUAL INTERFERENCE SYSTEM OF FOUR－DIMENSIONAL SPECIES

ＴＨＥＢＯＵＮＤＥＤＥＸＴＥＲＭＩＮＡＴＩＯＮＡＮＤＳＴＡＢＩＬＩＴＹＯＦＭＵＴＵＡＬＩＮＴＥＲＦＥＲＥＮＣＥＳＹＳＴＥＭＯＦＦＯＵＲ－ＤＩＭＥＮＳＩＯＮＡＬＳＰＥＣＩＥＳＨｏｕＧａｎ－ｓｈｅｎｇ（侯赣生）（Ｄｅｐｌ．ｏｆＰｈｙｓｉｃｓ,Ｊｉａｎｇｘ...     

SINGULAR PERTURBATION OF INITIAL BOUNDARY VALUE FROBLEMS OF REACTION DIFFUSlON EQUATION WITH DELAY

ＳＩＮＧＵＬＡＲＰＥＲＴＵＲＢＡＴＩＯＮＯＦＩＮＩＴＩＡＬＢＯＵＮＤＡＲＹＶＡＬＵＥＦＲＯＢＬＥＭＳＯＦＲＥＡＣＴＩＯＮＤＩＦＦＵＳｌＯＮＥＱＵＡＴＩＯＮＷＩＴＨＤＥＬＡＹＺｈａｎｇＸｉａｎｇ（张祥）（ＡｎｈｕｉＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ）Ｗｕ...     

Parallel Multisplitting AOR method for solving a class of system of nonlinear algebraic equations

ＰＡＲＡＬＬＥＬＭＵＬＴＩＳＰＬＩＴＴＩＮＧＡＯＲＭＥＴＨＯＤＦＯＲＳＯＬＶＩＮＧＡＣＬＡＳＳＯＦＳＹＳＴＥＭＯＦＮＯＮＬＩＮＥＡＲＡＬＧＥＢＲＡＩＣＥＱＵＡＴＩＯＮＳＢａｉＺｈｏｎｇｚｈｉ（白中治）（ＩｎｓｔｉｔｕｉｅｏｆＭａｔｈｅｍａｔｉｃｓＦｕ...     

SECOND ORDER EFFECTS IN AN ELASTIC HALF－SPACE ACTED UPON BY A NON－UNIFORM NORMAL LOAD

ＳＥＣＯＮＤＯＲＤＥＲＥＦＦＥＣＴＳＩＮＡＮＥＬＡＳＴＩＣＨＡＬＦ－ＳＰＡＣＥＡＣＴＥＤＵＰＯＮＢＹＡＮＯＮ－ＵＮＩＦＯＲＭＮＯＲＭＡＬＬＯＡＤＬｉｕＹｏｕ－ｗｅｎ（刘又文）（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓａｎｄＭｅｃｈ...     

Reciprocal theorem method for solving the problems of bending of thick rectangular plates

ＲＥＣＩＰＲＯＣＡＬＴＨＥＯＲＥＭＭＥＴＨＯＤＦＯＲＳＯＬＶＩＮＧＴＨＥＰＲＯＢＬＥＭＳＯＦＢＥＮＤＩＮＧＯＦＴＨＩＣＫＲＥＣＴＡＮＧＵＬＡＲＰＬＡＴＥＳＦｕＢａｏ－ｌｉａｎ（付宝连）Ｔａｎｗｅｎ－ｆｅｎｇ（谭文锋）（ＹａｎｓｈａｎＵｎｉｒｅｒｓｉｔ...     

The Solution to the Form of Poisson Equation by the Boundary Element Methods

ＳＯＬＵＴＩＯＮＴＯＴＨＥＦＯＲＭＯＦＰＯｌＳＳＯＮＥＱＵＡＴＩＯＮＢＹＴＨＥＢＯＵＮＤＡＲＹＥＬＥＭＥＮＴＭＥＴＨＯＤＳＬｉｕＸｉ－ｙｕｎ（刘希云）（ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙｏｆｓｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ）Ｎａｎｊｉｎｇ（Ｒ...     

EXISTENCE THEOREMS OF SOLUTIONS FOR TWO－POINT BOUNDARY VALUE PROBLEM OF SECOND ORDER ORDINARY DIFFERENTIAL EQUATIONS IN BANACH SPACES

ＥＸＩＳＴＥＮＣＥＴＨＥＯＲＥＭＳＯＦＳＯＬＵＴＩＯＮＳＦＯＲＴＷＯ－ＰＯＩＮＴＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＯＦＳＥＣＯＮＤＯＲＤＥＲＯＲＤＩＮＡＲＹＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＩＮＢＡＮＡＣＨＳＰＡＣＥＳＺｈａｎｇＳｈｉｓ...     

SINGULAR PERTURBATION FOR A NONLINEAR BOUNDARY VALUE PROBLEM OF FIRST ORDER SYSTEM

ＳＩＮＧＵＬＡＲＰＥＲＴＵＲＢＡＴＩＯＮＦＯＲＡＮＯＮＬＩＮＥＡＲＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＯＦＦＩＲＳＴＯＲＤＥＲＳＹＳＴＥＭＣｈｅｎＳｏｎｇｌｉｎ（陈松林）（ＲｅｃｅｉｖｅｄＡｐｒｉｌ８,１９８４;ＲｅｖｉｓｅｄＡｐｒｉｌ１５,１９...     

FORCED OSCILLATIONS OF BOUNDARY VALUE PROBLEMS OF HIGHER ORDER FUNCTIONAL PARTIAL DIFFERENTIAL EQUATIONS

ＦＯＲＣＥＤＯＳＣＩＬＬＡＴＩＯＮＳＯＦＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＳＯＦＨＩＧＨＥＲＯＲＤＥＲＦＵＮＣＴＩＯＮＡＬＰＡＲＴＩＡＬＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＪｉｎＭｉｎｇＺｈｏｎｇ（靳明忠），ＤｏｎｇＹｉｎｇ（董莹），Ｌｉ...     

THE EXAMINATION OF TURBULENCE MODELING WITH LES DATABASE

ＴＨＥＥＸＡＭＩＮＡＴＩＯＮＯＦＴＵＲＢＵＬＥＮＣＥＭＯＤＥＬＩＮＧＷＩＴＨＬＥＳＤＡＴＡＢＡＳＥＳｕＭｉｎｇ－ｄｅ（苏铭德）（ＱｉｎｇｈｕａＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ）Ｒ．Ｆｒｉｅｄｒｉｃｈ（ＬｅｈｒｓｉｒｈｌｆｕｒＦｌｕｉｄｓｍｅｃｈａ...     

Chaos synchronization for a class of nonequivalent systems with restrictive inputs via time-varying sliding mode

In this paper, the synchronization between Duffing and Van der Pol chaotic systems with control inputs constraint is investigated. In practice, the maximum admissible values of the control inputs are restrained. To solve this problem, based on time-varying sliding mode theory, we can obtain the best possible control quality without violating technical and environmental constraints by selecting the switching line parameters. Also a kind of extended state observer is used to compensate for the uncertainties of systems, using only the available synchronizing error. Then the controller becomes physically realizable based on the states of the observer, and can be used to synchronize between Duffing and Van der Pol chaotic systems. Finally, simulation results are presented to demonstrate the effectiveness of the proposed control scheme.     

A Simple Approach of Enlarging Convergence Regions of Perturbation Approximations

In this paper, a simple approach to enlarging convergence regions of perturbation approximations is proposed. Based on the so-called general Taylor theorems, this approach has a solid mathematical foundation. Moreover, it is rather simple to apply. Two nonlinear equations, the Riccati equation and the Van der Pol equation are used as examples to illustrate the validity and the great potential of this approach.     

Global bifurcations and chaos in a Van der Pol-Duffing-Mathieu system with three-well potential oscillator

Semi-analytical and semi-numerical method is used to investigate the global bifurcations and chaos in the nonlinear system of a Van der Pol-Duffing-Mathieu oscillator. Semi-analytical and semi-numerical method means that the autonomous system, called Van der Pol-Duffing system, is analytically studied to draw all global bifurcations diagrams in parameter space. These diagrams are called basic bifurcation diagrams. Then fixing parameter in every space and taking parametrically excited amplitude as a bifurcation parameter, we can observe the evolution from a basic bifurcation diagram to chaotic pattern by numerical methods. The project supported by the National Natural Science Foundation of China     

Adaptive nonsingular terminal sliding mode control for synchronization of identical Φ 6 oscillators

The main goal of this paper is to propose the adaptive nonsingular terminal sliding mode controllers for complete synchronization (CS) and anti-synchronization (AS) between two identical ?? ⁶ Van der Pol or Duffing oscillators with presentations of system uncertainties and external disturbances. Unlike directly eliminating the nonlinear items of synchronized error system for sliding mode control schemes in the literature, the proposed adaptive controllers can tackle the nonlinear dynamics without active cancellation. The controllers can be implemented without known bounds of system uncertainties and external disturbances. Meanwhile, the feedback gains are not determined in advance but updated by the adaptive rules. Sufficient conditions are given based on the Lyapunov stability theorem and numerical simulations are performed to verify the effectiveness of presented schemes. The results show that the chaotic synchronization can be achieved accurately by the chattering free control.     

Static feedback versus fractionality of the electrical elements in the Van der Pol circuit

In this paper, it is shown that by benefiting from a static feedback control signal it is possible to reduce the effect of fractionality of the electrical capacitors on the amplitude of the oscillations produced by a Van der Pol circuit. The averaging method is used in this paper for the behavior analysis of the approximated responses of the under study circuits. Numerical simulation results are presented to confirm the effectiveness of the proposed control technique.     

Zero-Hopf bifurcation in the Van der Pol oscillator with delayed position and velocity feedback

In this paper, we consider the traditional Van der Pol oscillator with a forcing dependent on a delay in feedback. The delay is taken to be a nonlinear function of both position and velocity, which gives rise to many different types of bifurcations. In particular, we study the Zero-Hopf bifurcation that takes place at certain parameter values using methods of center manifold reduction of DDEs and normal form theory. We present numerical simulations that have been accurately predicted by the phase portraits in the Zero-Hopf bifurcation to confirm our numerical results and provide a physical understanding of the oscillator with the delay in feedback.     

Effect of Multi-Scale Porosity in Local Permeability Modelling of Non-Crimp Fabrics

The influence of multi-scale porosity of fibre reinforcements on local permeability is investigated, in order to determine the possibility of simplifying permeability models for more efficient permeability calculations. Unit cell models of a biaxial Non-Crimp Fabric are developed and used to investigate, whether or not the porous bundles can be excluded, when modelling the local permeability. Numerical accuracy of calculations is controlled to guarantee the quality of the results and the conclusions drawn from them. It is found that fibre bundles with high fibre density can be excluded from permeability models, while bundles with low fibre volume fractions need to be included. A new method to model the local permeability of multi-scale reinforcements is developed and verified for low fibre density in the bundles. In this method, the effects of the flow inside the fibre bundles are included through modifications of the boundary conditions of a single-scale model representing the interbundle regions. The local permeability of multi-scale reinforcements can, therefore, be calculated by models with simplified fluid domains for all fibre bundle porosities, instead of being calculated by models consisting of the entire multi-scale geometry.     

非线性最小二乘跟踪的对偶变量变分方法

最小二乘跟踪方法是近几年提出的一种计算动力系统跟踪轨迹的方法.基于最小二乘跟踪的灵敏度分析算法可以有效避免传统的非线性系统灵敏度分析方法中的病态初值问题,因此其在混沌系统灵敏度分析方面有着重要的应用.针对非线性的最小二乘跟踪问题,首先将其重新描述为带有约束的非线性最优控制问题,引入协态变量并将系统的哈密顿函数表示为关于状态变量和协态变量的函数.然后将目标函数的积分时间离散化,根据对偶变量变分原理,以离散区间两端的状态变量作为独立变量,用Lagrange插值多项式近似离散区间内的状态变量和协态变量,进而将非线性最优控制问题转化为求解非线性方程组问题.这种算法无需对原问题做线性化处理,避免了复杂的线性化过程以及可能因此造成的误差,同时为求解非线性最小二乘跟踪问题提供了新的思路.根据最小二乘方法可以得到两条设计参数有微小变化的状态轨迹,基于这两条状态轨迹可进一步计算出系统关于设计参数的灵敏度,范德波振子作为数值算例验证了该方法在求解最小二乘跟踪问题以及计算非线性系统灵敏度时的有效性.      

Nonstationary probability densities of strongly nonlinear single-degree-of-freedom oscillators with time delay

The approximate nonstationary probability density of a nonlinear single-degree-of-freedom (SDOF) oscillator with time delay subject to Gaussian white noises is studied. First, the time-delayed terms are approximated by those without time delay and the original system can be rewritten as a nonlinear stochastic system without time delay. Then, the stochastic averaging method based on generalized harmonic functions is used to obtain the averaged Itô equation for amplitude of the system response and the associated Fokker–Planck–Kolmogorov (FPK) equation governing the nonstationary probability density of amplitude is deduced. Finally, the approximate solution of the nonstationary probability density of amplitude is obtained by applying the Galerkin method. The approximate solution is expressed as a series expansion in terms of a set of properly selected basis functions with time-dependent coefficients. The proposed method is applied to predict the responses of a Van der Pol oscillator and a Duffing oscillator with time delay subject to Gaussian white noise. It is shown that the results obtained by the proposed procedure agree well with those obtained from Monte Carlo simulation of the original systems.     

Slow passage through canard explosion and mixed-mode oscillations in the forced Van der Pol’s equation

This paper investigates the emergence of mixed-mode oscillations (MMOs) in the forced Van der Pol’s equation. It is found that the MMOs studied here can be classified as a slow passage through canard explosion, which is different from the usual fast-slow bursters. We first consider the external forcing as a control parameter and study its influence on the Van der Pol’s equation with constant forcing (VPCF). Then we briefly discuss the famous canard phenomenon in VPCF. The results of these analysis, together with the “transformed phase diagram,” are applied to the forced Van der Pol’s equation, which shows that the canard explosion and the external forcing plays an important role in the generation of MMOs, that is, the MMOs are created since the external forcing slowly and periodically visits the rest and spiking areas of VPCF.