Adaptive fuzzy backstepping control design for a class of pure-feedback switched nonlinear systems

In this paper, an adaptive fuzzy output tracking control approach is proposed for a class of single input and single output (SISO) uncertain pure-feedback switched nonlinear systems under arbitrary switchings. Fuzzy logic systems are used to identify the unknown nonlinear system. Under the framework of the backstepping control design and fuzzy adaptive control, a new adaptive fuzzy output tracking control method is developed. It is proved that the proposed control approach can guarantee that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded (SGUUB) and the tracking error remains an adjustable neighborhood of the origin. A numerical example is provided to illustrate the effectiveness of the proposed approach.     

Excel在最小二乘法不确定度评定中的应用

对测量不确定度的评定,采用最小二乘法的计算非常复杂而繁琐,即使用计算器计算,也很费时且易出差错。但应用Excel软件,特别是充分发挥其函数功能,进行不确定度评定,不仅明显加快了计算速度,且大大减少了错误的发生,实践表明,用Excel计算所得结果与文献报道的结果一致。     

Transversal homoclinic orbits and chaos for partial functional differential equations

The persistence of degenerate homoclinic orbit is considered for parabolic functional differential equations with small periodic perturbations. Bifurcation functions constructed between two finite-dimensional spaces are obtained. The zeros of the function correspond to the existence of the homoclinic orbit for the perturbed systems. Some applicable conditions are given to ensure that the functions are solvable. Moreover, We show that the homoclinic solution for the perturbed system is transversal and hence the perturbed system exhibits chaos.     

Optical soliton with damping and frequency chirping in fibre media

Nonlinear Schrödinger (NLS) equation which governs the propagation of single field in the fibre medium with pulse chirping and gain (loss) is considered. The integrability condition of NLS equation is arrived from the linear eigenvalue problem and is studied by using the Painlevé singularity structure analysis. From the Lax pair, soliton solution is constructed by using the Darboux–Bäcklund transformation technique. From the results, we show that the soliton is alive, i.e., pulse area is conserved with the inclusion of damping and pulse chirping effects.     

Spectral galerkin approximation of couette-taylor flow

Axisymmetric Couette-Taylor flow between two concentric rotating cylinders was simulated numerically by the spectral method. First, stream function form of the Navier-Stokes equations which homogeneous boundary condition was given by introducing Couette flow. Second, the analytical expressions of the eigenfunction of the Stokes operator in the cylindrical gap region were given and its orthogonality was proved. The estimates of growth rate of the eigenvalue were presented. Finally, spectral Galerkin approximation of Couette-Taylor flow was discussed by introducing eigenfunctions of Stokes operator as basis of finite dimensional approximate subspaces. The existence, uniquence and convergence of spectral Galerkin approximation of nonsingular solution for the steady-state Navier-Stokes equations are proved. Moreover, the error estimates are given. Numerical result is presented.     

Couette-Taylor流的谱Galerkin逼近

利用谱方法对轴对称的旋转圆柱间的Couette-Taulor流进行数值模拟．首先给出Navier-Stokes方程流函数形式,利用Couette流把边界条件齐次化．其次给出Stokes算子的特征函数的解析表达式,证明其正交性,并对特征值进行估计．最后利用Stokes算子的特征函数作为逼近子空间的基函数,给出谱Galerkin逼近方程的表达式．证明了Navier-Stokes方程非奇异解的谱Galerkin逼近的存在性、唯一性和收敛性,给出了解谱Galerkin逼近的误差估计,并展示了数值计算结果．     

Adaptive robust fuzzy control for a class of uncertain chaotic systems

In this paper, the output feedback control of uncertain chaotic systems is addressed via an adaptive robust fuzzy approach. Fuzzy logic systems are employed to approximate uncertain nonlinear functions in the chaotic systems. Because only partial information of the system’s states is needed to be known, an observer is given to estimate the unmeasured states. Compared with the existing results in the observer design, the prior knowledge on dynamic uncertainties is relaxed and a class of more general chaotic systems is considered as well as robustness to the approximation error is improved. It can be proven that the closed-loop system is stable in the sense that all the variables are bounded. Simulation example for the unified chaotic systems is given to verify the effectiveness of the proposed method. This work was supported in part by the National Natural Science Foundation of China (60874056) and the Foundation of Educational Department of Liaoning Province (2008312).     

4-甲氧基-3-[3-(吗啉-4-基)丙氧基]苯甲腈的合成研究

以3-羟基-4-甲氧基苯甲醛为原料,在甲酸、甲酸钠、盐酸羟胺作用下,将醛基转化为氰基,在含有碳酸钾的DMF中,所得化合物与N-(3-氯丙基)吗啉反应得目标化合物,总收率为87.5%。产物结构由1HNMR表征。本方法具有操作简单、易于纯化、收率高等特点,为工业化生产提供实验基础。     

奋乃静与甲酚红的荷移反应研究

采用光度法研究了电子给予体奋乃静与电子接受体甲酚红之间的荷移反应,据此建立了荷移光度法测定奋乃静含量的方法.实验表明,奋乃静与甲酚红在丙酮介质中,室温条件下即可形成稳定的1:2型荷移络合物,该络合物的最大吸收波长为434nm,表观摩尔吸光系数为1.19×10<'4>L·mol<'-1>·cm<'-1>.奋乃静的质量浓度...