Nonlinear Gains Recursive Sliding Mode Dynamic Surface Control with Integral Action

In this paper, by introducing a function with nonlinear gains and developing sliding surfaces with integral action in the dynamic surface control (DSC) recursive procedure, a novel DSC strategy is proposed. The drawbacks of conventional DSC methods, such as being sensitive to the design constant of the first order low‐pass filter and being unable to achieve zero steady‐state error for step reference signal, are overcome. Moreover, improvement of transient performance and reduction of control effort can be obtained. The stability analysis shows that the proposed new approach can guarantee semi‐global uniform ultimate boundedness (SGUUB) of all closed‐loop signals and that the ultimate tracking error bound in regulation can be made arbitrarily small.     

A New Method for Getting Rational Approximation for Fractional Order Differintegrals

In this paper a new algorithm is presented to calculate the poles and zeros to approximate a fractional order (FO) differintegral (s^±α,α∈(0,1)) by a rational function on a finite frequency band ω∈(ω_l,ω_h). The constant phase property of the FO differintegral is the basis for development of the algorithm. Interlacing of real poles and zeros is used to achieve the constant phase. The calculations are done using the asymptotic Bode phase plot. A brief investigation is made to get a good approximation for the Bode phase plot. Two design parameters are introduced to keep the average phase close to the desired phase angle and to keep the error within the allowed bounds. A study is done to empirically understand the relationship between the error and the design parameters. The results thus obtained help in the further calculations. The algorithm is computationally simple and inexpensive, and gives a fairly good approximation of fractance frequency response on the specified frequency band.     

改进的分层A*算法在停车场路径寻优中的应用

在大型停车场车位路径寻优中,传统的评价指标是把距离最短作为最优指标,并没有考虑实际路况,为此引入了切实可行的时间较优评价指标,既能简化引导系统硬件设计,又能节省软件开销;首先,建立了停车场网络图R (P,C,D,V)数学模型,并把网络中的所有节点分成两层,分别构建了不同的估价函数,采用改进的A*算法,提高了以时间较优为评价指标的路径搜索效率和搜索精度;最后,程序运行结果表明,针对不同的路段属性参数,算法总能较快的找到时间较优路径.     

交互式遗传程序设计在作曲中的应用

针对目前的算法作曲系统普遍存在的局限性,提出一种交互式遗传程序设计(Interactive Genetic Programming,IGP)的作曲方法.介绍了用交互式遗传程序设计进行作曲的原理、步骤.提出了一种交互式遗传程序乐曲生成系统,用人做为适应度函数,用遗传程序设计的方法来产生乐曲片段.把乐曲片段交给人进行评价后,人对乐曲是否参与下一代进化进行取舍,直至产生理想的乐曲.实验结果显示:得到的乐曲片段较之前各种乐曲生成系统得到的乐曲更连贯,能够符合人的欣赏习惯.     

C语言函数教学方法探讨

函数是程序的基本组成单位,是C语言程序设计课程的核心部分。结合多年的教学实践,探讨了函数教学的一些行之有效的教学方法,供同行参考。     

Key management in tree shaped hierarchies

ABSTRACT

We refer to an access control system based on subjects and objects. Subjects are active entities, e.g. processes, while objects are passive entities, e.g. messages exchanged between the nodes of a distributed computing environment. The system is partitioned into security classes organized into a tree shaped hierarchy. A subject assigned to a given class can access the objects in this class and in all the classes that descend from this class in the class hierarchy. To this aim, a key is associated with each class. A mechanism of the protection system, called key derivation, allows a subject that holds the key of a given class to transform this key into the keys of the descendant classes. This mechanism is based on a single, publicly known one-way function. If the class hierarchy is modified, by adding a new class or deleting an existing class, the necessary form of key redistribution is partial, and is limited to the classes in the subtree of the root that is involved in the change.     

High‐order sliding mode control design based on adaptive terminal sliding mode

High‐order sliding mode control techniques are proposed for uncertain nonlinear SISO systems with bounded uncertainties based on two different terminal sliding mode approaches. The tracking error of the output converges to zero in finite time by designing a terminal sliding mode controller. In addition, the adaptive control method is employed to identify bounded uncertainties for eliminating the requirement of boundaries needed in the conventional design. The controllers are derived using Lyapunov theory, so the stability of the closed‐loop system is guaranteed. In the first technique, the developed procedure removes the reaching phase of sliding mode and realizes global robustness. The proposed algorithms ensure establishment of high‐order sliding mode. An illustrative example of a car control demonstrates effectiveness of the presented designs. Copyright © 2011 John Wiley & Sons, Ltd.     

On stability delay bounds of simple input-delayed linear and non-linear systems: Computational results

This paper deals with the problem of delay size stability analysis of single input-delayed linear and nonlinear systems. Conventional reduction, reduction linked by sliding mode, and linear memoryless control approaches are used for simple input-delayed systems to obtain the stability conditions. Several first order examples are investigated systematically to demonstrate the capabilities and limitations of the advanced stability analysis techniques including Lyapunov-Krasovskii functionals, Newton-Leibniz formula, and a newly addressed Lagrange mean value theorem. Numerical comparative results show the usefulness and effectiveness of the advanced delay size analysis techniques proposed in this paper.     

基于MATLAB的水下地形冲刷过程模拟研究

基于水下地形实时监测技术,对河工模型水下地形冲刷发展过程进行了分析,在研究水下地形冲刷过程中,采用MATLAB为平台,对采集的数据进行了过滤处理,通过基于原始递归函数理论的曲线(面)拟合法对选取点进行插值得出水下地形冲刷过程随时间的变化曲线,用插值曲线对水下地形发展过程进行模拟,再与实测数据进行分析比较,结果证明该模拟方法可行,并对水下地形的冲刷过程研究具有一定参考价值。     

基于改进型MF-DFA的月径流序列多重分形分析

应用改进的多重分形消除趋势波动分析法对长江流域某水文站多年月径流资料进行分析计算,结果显示,月径流序列具有长程相关性和多重分形特征,并采用二项倍增串级模型,对其多重分形谱拟合,表明月径流序列具有较强的多重分形性。通过对其初始序列、重排序列和替代序列进行对比分析,揭示出月径流序列多重分形特征是序列本身的长程相关性和胖尾概率分布共同作用的结果,且胖尾概率分布起主要作用。