Flocking of multi‐agent nonholonomic systems with unknown leader dynamics and relative measurements

In this paper, we consider the distributed flocking control problem of multi‐agent nonholonomic systems with a virtual leader whose dynamics is unknown; state information is time varying and not available to all agents under both fixed and switching topologies. On the basis of the relative velocity and orientation information of neighboring agents, two distributed discontinuous control protocols are designed for fixed and switching topologies, respectively. By using tools from algebraic graph theory and nonsmooth analysis, the proposed distributed discontinuous control protocols guarantee that the velocities and orientations of the agents exponentially converge to the velocity and orientation of the virtual leader, respectively, while ensuring collision avoidance of the whole group, if the interaction graph among agents is undirected and the virtual leader with bounded time‐varying velocity has directed paths to other agents. Finally, numerical simulations are provided to illustrate the effectiveness of the theoretical results. Copyright © 2017 John Wiley & Sons, Ltd.     

基于点对匹配的印刷电路板CT图像配准方法

针对PCB CT图像在拼接时存在较多相似区域无法有效配准的问题,提出一种基于点对匹配的方法.首先根据邻近特征点生成特征点对,并简化一种快速低维的特征描述子KPB-SIFT来描述特征点对,然后通过规定点对方向和点对分类匹配降低误匹配,最后给出一种匹配点方向约束条件,并基于该条件提出一种错误匹配点抑制算法提取正确匹配点.实验结果表明,该算法在保持较低时间复杂度的同时,匹配正确率达到95.58％,能够提取较多均匀分布的正确匹配点,从而能有效地解决PCB CT图像的配准问题.     

共享存储器交换机的性能分析

交换机是分组网中的一个重要组成部分,对于分组网的性能有着很大影响。介绍共享存储器交换机的三种不同实现方法以及多播的实现过程．同时以排队论的知识为理论分析基础,介绍排队论中的生灭过程模型,状态转移模型和爱尔兰呼损模型,并对状态转移的稳态特性以及共享存储器结构的交换机的丢包率公式给出推导。对所做的工作做简要的总结,并指明未来的研究重点．     

一种新的指纹图像合成分割法

在研究和分析传统方差法和最大类间方差法的基础上,提出了一种传统方差法和最大类间方差法相结合的分块处理分割算法。该算法首先求出整个指纹图像的方差,然后计算每一子块的方差。若方差小于整个图像的方差则用方差法对图像进行分割,否则用最大类间方差法进行分割。最后再对图像进行平滑处理。实验结果表明,相对于传统分割方法,该方法无需根据经验选取阈值,能较准确地分割出前景和背景,抗噪能力强,对高对比度和低对比度的图像均具有很好的分割效果。     

图模型在彩色纹理分类中的应用

纹理分析中往往将彩色图像转换为灰度图以降低计算复杂度,这样就忽略了颜色信息。而利用主成分分析 的方法来降维彩色纹理,则可以尽可能地保留颜色和纹理信息。高斯图模型(Uaussian Graphical Models, GGM)可以 很好地描述有交互作用的高维数据,因此可用来建立图像纹理模型。根据局部马尔可夫性和高斯变量的条件回归之 间的关系,可将复杂的模型选择转变为较简单的变量选择。通过惩罚正则化方法,其部域选择和参数佑计可同步进 行,然后提取纹理特征进行彩色纹理分类,实验显示其具有很好的效果。因此,结合主成分分析和高斯图模型来构建 彩色纹理模型有很好的发展前景。     

无线寻呼系统的设计与实现

结合寻呼系统的特点,对寻呼系统的总体设计和功能模块进行详细的论述,同时阐明了无线寻呼的基本过程,并对保证寻呼系统的高效性,提高寻呼系统可靠性,稳定性所采取的 全面地研究。     

On impulsive control of a periodically forced chaotic pendulumsystem

We consider impulsive control of a periodically forced pendulum system which has rich chaos and bifurcation phenomena. A new impulsive control method for chaos suppression of this pendulum system is developed. Some simple sufficient conditions for driving the chaotic state to its zero equilibrium are presented, and some criteria for eventually, exponentially asymptotical stability are established. This work provides a rigorous theoretical analysis to support some early experimental observations on controlling chaos in the periodically forced pendulum system     

无线传感器网络及其应用研究

阐述了无线传感器网络的组成及其主要特点,对其关键性问题进行了探讨。最后,介绍了无线传感器网络在军事和民用领域的应用情况。     

Output feedback stabilization for time-delay nonlinear interconnected systems using neural networks.

In this paper, dynamic output feedback control problem is investigated for a class of nonlinear interconnected systems with time delays. Decentralized observer independent of the time delays is first designed. Then, we employ the bounds information of uncertain interconnections to construct the decentralized output feedback controller via backstepping design method. Based on Lyapunov stability theory, we show that the designed controller can render the closed-loop system asymptotically stable with the help of the changing supplying function idea. Furthermore, the corresponding decentralized control problem is considered under the case that the bounds of uncertain interconnections are not precisely known. By employing the neural network approximation theory, we construct the neural network output feedback controller with corresponding adaptive law. The resulting closed-loop system is stable in the sense of semiglobal boundedness. The observers and controllers constructed in this paper are independent of the time delays. Finally, simulations are done to verify the effectiveness of the theoretic results obtained.     

基于测量的接纳控制研究

与传统的接纳控制算法相比,基于测量的纳控制有诸多优点,首先它无需知识应用的流量模型,其次它能动态适应网络的负载变化,提高网络资源的利用率。文中分析了基于测量的接纳控制的基本思想,并在此基础上提出和实现了一种自适应的接纳控制算法（Adaptive Measurement-Based Admission Control,AMBAC).作者通过实验对该算法进行了验证,发现在系统资源利用率（或接纳能力）接近的情况下,与传统的（固定时间窗口的）,MBAC相比,AMBAC能达到更低的平均分组丢失率。