Leader-following consensus of multi-agent systems under directed communication topology via distributed adaptive nonlinear protocol

In this paper, we study the leader-following consensus problem of general linear multi-agent systems under directed communication topology. To avoid using any global information, an adaptive nonlinear protocol is proposed based only on the relative state information. It is proved that, for any directed communication graph that contains a spanning tree with the root node being the leader agent, the proposed control law solves the leader-following consensus problem. A numerical example is provided to illustrate the effectiveness of the theoretical results.     

Necessary and sufficient conditions for solving consensus problems of double‐integrator dynamics via sampled control

In this paper, consensus problems of double‐integrator dynamics via sampled control are investigated. The sampled control protocol is induced from continuous‐time linear consensus protocol by using periodic sampling technology and zero‐order hold circuit. With the obtained sampled control protocol, the continuous‐time multi‐agent system is equivalently transformed into a linear discrete‐time system. Necessary and sufficient conditions are given to guarantee that all the agents asymptotically travel with zero relative positions and common velocities. Furthermore, consensus problem with continuous‐time consensus protocol is re‐analyzed. A necessary and sufficient condition is also obtained which is consistent with the special case when the sampling period tends to zero. The effectiveness of these algorithms is demonstrated through simulations. Copyright © 2009 John Wiley & Sons, Ltd.     

基于能量整形方案实现具有通讯时滞欠驱动Euler-Lagrange网络的一致性

本文主要基于能量整形方案研究具有通讯时滞网络化欠驱动Euler-Lagrange (EL)系统的一致性问题,通过利用阻尼注入和互连分配的无源控制(PBC)技术,在有向连通网络拓扑下提出了一个简单的分布式协议,来实现在无引导者和有引导者-跟随者两种情形下欠驱动EL网络的一致性. 本文提出的一致性能量整形方案的主要特点是有机地整合了系统欠驱动和驱动部分以及控制器三部分能量作为整个系统的总能量,这个总能量被利用作为一个合适的Lyapunov函数,它能够充分确保网络化欠驱动EL系统达到所期望的分布式一致性. 最后,通过由欠驱动EL网络所描述柔性关节机械臂系统的数值模拟,来分析通讯时滞对一致性的效应和验证所提出控制算法的正确性.     

Robust consensus of multi-agent systems with noise

The consensus problem of multi-agent systems has attracted wide attention from researchers in recent years, following the initial work of Jadbabaie et al. on the analysis of a simplified Vicsek model. While the original Vicsek model contains noise effects, almost all the existing theoretical results on consensus problem, however, do not take the noise effects into account. The purpose of this paper is to initiate a study of the consensus problems under noise disturbances. First, the class of multi-agent systems under study is transformed into a general time-varying system with noise. Then, for such a system, the equivalent relationships are established among (i) robust consensus, (ii) the positivity of the second smallest eigenvalue of a weighted Laplacian matrix, and (iii) the joint connectivity of the associated dynamical neighbor graphs. Finally, this basic equivalence result is shown to be applicable to several classes of concrete multi-agent models with noise. Supported by the National Natural Science Foundation of China (Grant Nos. 60821091, 60804043, 60574068), and the Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KJCX3-SYW-S01)     

在线巴林特小组工作与学习中国专家共识

巴林特小组旨在帮助医务工作者得到情感支持及不同角度的反馈,启发反思,缓解职业耗竭。新型冠状病毒肺炎疫情期间,医务人员难以进行传统形式的现场巴林特小组工作。参考近年来国际经验,中国各地巴林特组长尝试采用网络方式开展在线巴林特小组工作。为进一步规范网络在线工作方式,中国医师协会精神科医师分会医患关系工作委员会通过两轮讨论,对在线巴林特小组的工作原则和形式取得了一致意见,并对在线巴林特小组工作流程、使用网络平台进行示范和观摩学习、注意事项以及未来发展方向等达成了共识。     

The minority slowness effect: Subtle inhibitions in the expression of views not shared by others.

Five studies revealed that people who hold the minority opinion express that opinion less quickly than people who hold the majority opinion. The difference in speed in the expression of the minority and majority opinions grew as the difference in the size of the minority and majority grew. Also, those with the minority view were particularly slow when they assumed the majority to be large, whereas the opposite was true for those with the majority view. The minority slowness effect was not found to be linked to attitude strength, nor was it influenced by anticipated public disclosure of the attitude. The effect is discussed in the context of implicit conformity pressures and the limited buffering effect of false consensus assumptions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of sequence motifs from a set of porteins with related function

The automatic identification of motifs associated with a givenfunction is an important challenge for molecular sequence analysis.A method is presented for the extraction of such patterns fromlarge sets of unaligned sequences with related but general function,for example, a set of heat shock proteins. In such a set ofproteins there can often be several subfamilies each characterizedby one or more distinct motifs. The aim is to develop computationaltools to identify these motifs. The algorithm presented locateshigh frequency words of length k with a given number of positions,r, fixed. Statistics for a binomial distribution are used toassess the significance of the words. The high-frequency wordsare clustered and highly populated clusters retained. The compositionof the clusters is displayed graphically. A set of motifs associatedwith the sequence family can automatically be extracted. Themethod is benchmarked on a set of 106 heat shock sequences anda set of 257 toxin sequences. It is shown to recover previouslyidentified motifs.     

量化状态信息下多智能体Gossip算法及分布式优化

基于量化状态信息的异步随机Gossip算法大多以均匀选择概率的时间模型为基础,未充分考虑网络拓扑结构对局部信息传递的影响。为此,该文提出了一种以非均匀选择概率为时间模型的改进算法。首先给出了非均匀选择概率下的多智能体系统时间模型,在随机性量化策略下给出了一致性误差的收敛性质;并讨论了量化精度和概率化权重矩阵第2大特征值对一致性误差收敛速度的影响,进而利用投影次梯度给出了选择概率的分布式优化方法。仿真结果表明,该基于量化状态信息的算法可通过选择概率的分布式优化,提高一致性误差的收敛速度。     

无线传感器网络分布式一致时间同步协议的收敛分析及加速设计

该文研究了基于分布式一致的无线传感器网络时间同步协议的收敛和加速问题。通过将其同步迭代过程映射到马尔可夫链的状态转移过程,推导出了分布式一致时间同步协议在循环网中的收敛速度与节点邻居数和网络规模有关。Matlab仿真实验表明该结论对类均匀规则网和类均匀网也是正确的。此外,对于类均匀网,邻居数分布也会影响协议的收敛速度。因此该文提出了基于改变网络邻居数分布的加速算法来提高分布式一致时间同步协议的收敛速度。规模为100个节点的类均匀网络实验结果表明,该文提出的加速算法在没有显著改变节点平均传输半径的情况下可使分布式一致时间同步协议的收敛迭代次数降低约25%。     

网络志愿者协会:高校校园网舆论引导的新兴主体

高校校园网作为青年学生经常访问的网站之一,直接反映了当代青年学生的思想观念和价值取向。它在给学校师生带来方便、快捷服务的同时,在网络语言和网络道德方面也存在着明显的问题和不足,急需一种切实可行的措施来加强对高校校园网舆论的监督和引导,而网络志愿者协会的构建将对高校校园网络舆论的引导有着极其重要的意义。