Observer-based sliding mode control for a class of uncertain nonlinear neutral delay systems

In this paper, the observer-based sliding mode control (SMC) problem is investigated for a class of uncertain nonlinear neutral delay systems. A new robust stability condition is proposed first for the sliding mode dynamics, then a sliding mode observer is designed, based on which an observer-based controller is synthesized by using the SMC theory combined with the reaching law technique. Then, a sufficient condition of the asymptotic stability is proposed in terms of linear matrix inequality (LMI) for the overall closed-loop system composed of the observer dynamics and the state estimation error dynamics. Furthermore, the reachability problem is also discussed. It is shown that the proposed SMC scheme guarantees the reachability of the sliding surfaces defined in both the state estimate space and the state estimation error space, respectively. Finally, a numerical example is given to illustrate the feasibility of the proposed design scheme.     

二阶非线性中立微分方程的振动

考虑二阶中立时滞微分方程 [a(t)(x(t) p(t)(t-τ))’]’ q(t)f(x(t-σ))=0 (E)其中τ与σ是非负常数,a,p,q∈C([t_0,∞)R)且f∈C(R,R),提出了方程(E)的某些新的振动条件。     

轻声的宏观历史发展

异地共时的各方言轻声构成了一个历时的轻声序列。音段的弱化将导致音节的缩短变质,并融合进前音节中,声调的发展则由独立的特定变调转为短调,最终彻底失落本调。轻声起于声调退化,是声调的消亡而非新增。     

Dynamical output feedback stabilization for neutral systems with mixed delays

This paper is concerned with the issue of stabilization for the linear neutral systems with mixed delays. The attention is focused on the design of output feedback controllers which guarantee the asymptotical stability of the closed-loop systems. Based on the model transformation of neutral type, the Lyapunov-Krasovskii functional method is employed to establish the delay-dependent stability criterion. Then, through the controller parameterization and some matrix transformation techniques, the desired parameters are determined under the delay-dependent design condition in terms of linear matrix inequalities （LMIs）, and the desired controller is explicitly formulated. A numerical example is given to illustrate the effectiveness of the proposed method.     

多滞量具有正负系数的一阶中立型时滞微分方程的稳定性

本文考虑一阶中立型时滞微分方程(1): [x(t)+sum from i=1 to n_1ci(t)x(t-r_i)]~′+sum from k=1 to n_2Pk(t)x(t-τ_k)-sum from j=1 to n_3qj(t)x(t-σ_j)=0的稳定性。这里均为非负实数,我们建立了此方程的一个稳定性结果,较文献[6]讨论得更广泛,所得结论更深刻。     

乙二胺四乙酸酐修饰玉米芯对阳离子染料的吸附行为

本文选择乙二胺四乙酸酐（EDTAD）作为修饰剂对玉米芯进行化学接枝改性,同时对修饰玉米芯的吸附行为进行了研究。实验数据表明与未修饰玉米芯相比,EDTAD修饰玉米芯对两种阳离子染料的吸附容量明显增加。吸附等温线实验表明,Langmuir模型可较好描述此吸附过程,动力学实验表明,准二级方程适合描述此吸附过程。除此之外,还探讨了这种改性玉米芯的再生率。     

二阶中立型逐段常变量微分方程的伪ω周期解

给出了二阶中立型逐段常变量微分方程d^2/dt^2（x（t）＋p（t）x（t-1））=qx（2[t＋1/2]＋g（t,x（t）,x（[t]））d^2/dt^2（x（t）＋p（t）x（t-1））=qx（2[t＋1/2]＋f（t）的伪ω周期解存在唯一性的充分条件.     

一类中立型差分方程存在正解的判则

考虑中立型差分方程Δ（xn-rn/rn-k xn-k qnxn-l=0,n≥n。给出了方程（＊）的各类正解存在的判则。