最优非单位步长无向双环网络G(N;±r,±s)的构造*

创造性地将直角坐标系引入无向双环网络的研究,通过直角坐标系,系统地研究无向双环网络G(N;±r,±s)的直径、平均直径,得出平均直径的下界。提出最优无向双环网络BestG(N;±r,±s)(直径、平均直径均达到下界)的构造方法,并研究步长r、s与其直径之间的关系。与传统L型瓦方法在无向双环网络研究中相比,该方法克服了其不足,大大提升了无向双环网络的研究水平。     

无向双环网络G(N;±r,±s)的图形仿真算法

传统的L形瓦仿真方法无法直接用于研究无向双环网络。针对上述问题,将直角坐标系引入无向双环网络中,提出一种新的图形仿真算法。利用该算法可以快速仿真出无向双环网络G(N;±r,±s)的图形,同时标注其直径、平均距离及节点的具体分布。通过研究仿真图形,得出单位步长无向双环网络G(N;±r,±s)直径、平均距离的分布规律。     

几类特殊有向单位步长双环网络的寻径算法

直径的求解是双环网络的最关键问题,为更好求解双环网络直径,文中选择一个步长为1的有向单位步长双环网络,针对另一个步长h的取值为最小值2,中间值N/2、(N/2)+1(N为偶数)或者中间值(N+1)/2(N为奇数)和最大值N-1这3种情况所构成的几类双环网络,给出了寻径算法,对这几种算法的特点进行了分析和比较,并对这几种算法的时间和空间特性进行了比较分析,得出它们的时间复杂度和空间复杂度都是Ω(N/2)。     

最优无向双环网络G（N；±1，±s）的构造

创造性地将直角坐标系引入无向双环网络的研究,通过直角坐标系,系统研究无向双环网络G（N;±1,±s）的仿真图形,提出最优无向双环网络BestG（N;±1,±s）（直径、平均直径均达到下界）的构造方法并研究步长s和其直径之间的关系。与传统L型瓦方法在无向双环网络研究中相比,该方法克服其不足,大大提升了无向双环网络的研究水平,相关研究在国内外文献中尚未见到。     

无向双环网络G(N;±1,±s)的直径求解算法

提出无向双环网络G(N;±1,±s)的直径求解算法,利用VB6.0作为编程语言、SQLServer2000作为数据库来实现这一算法,对任意给定N,而2≤s≤N-1的这样一族无向双环网络的直径都可以计算出来,结果存入数据库,并且利用VB6.0的控件MSChart来模拟显示计算结果。找出了该族无向双环网络直径的分布特点:具有最大值、最小值和中间对称性;对任意N,有不少s使得G(N;±1,±s)紧优或几乎紧优。验证了Boesch和Wang等提出的无向双环网络G(N;±1,±s)的直径下界,给出了一个新的直径上界公式。     

无向双环网络G(N;±1,±s)的直径求解算法

提出无向双环网络G(N;±1,±s)的直径求解算法,利用VB6.0作为编程语言、SQL Server2000作为数据库来实现这一算法,对任意给定N,而2≤s≤N-1的这样一族无向双环网络的直径都可以计算出来,结果存入数据库,并且利用VB6.0的控件MSChart来模拟显示计算结果.找出了该族无向双环网络直径的分布特点:具有最大值、最小值和中间对称性;对任意N,有不少s使得G(N;±1,±s)紧优或几乎紧优.验证了Boesch和Wang等提出的无向双环网络G(N;±1,±s)的直径下界,给出了一个新的直径上界公式.     

双环网络直径点和宽直径点的分布特性

针对单个有向单位步长双环网络G(N;1,h),根据其直径和宽直径的定义,并借助其等价L形瓦进行直径和宽直径路由的构造,证明了任意双环网络的直径点和宽直径点均小于或等于2个;证明了直径点一定分布在L形瓦的第一象限内,宽直径点一定分布在L形瓦的两个坐标轴上.对于一族有向单位步长双环网络G(N;1,2≤h≤N-1),随着步长h的递增,该族双环网络路由的节点顺序具有由小到大变为由大到小的特点,借助VB6.0编程仿真了该族双环网络直径点和宽直径点的分布图,发现其直径点和宽直径点具有波动下降的特征;直径点往往大于宽直径点;步长h在中间处两者的值最大;对于某个双环网络,如果直径点有两个,则其宽直径点必有两个.     

有向双环网和无向双环网直径规律的对比

近年内双环网络越来越广泛地被应用于局域网中.目前得到广泛的认同的是双环网络最小直径的几种求解方法,即是指对于任意给定N,而2≤S≤N-1的这样一族双环网络中找到任意节点对间的最小距离中的最大者.在可以轻松计算出双环网络直径以后,文中将给出一个新的行之有效的算法来比较有向双环网和无向双环网直径的规律.     

一类有向双环网络的最优单播路由算法

有向双环网络G(N;1,h)(N是节点数，1和h是步长)是重要的互联网络结构。给出了有向双环网络G(N;1,h)的若干性质。作为这些性质的两个应用，给出一类有向双环网络的直径公式，以及这类有向双环网络的单播路由算法，这个算法是简单且最优的。     

有向双环网络最优路由算法

最优路由的研究对于网络节点的传输具有重要意义,但关于有向双环网络节点的最优路由研究,目前尚无统一的算法.现有有向双环网络的最优路由算法,主要集中在单位步长双环网络及一些特殊双环网络上,对于为数较多的非单位步长有向双环网络最优路由的研究较少.已知有向双环网络的MDD图形为L形瓦,基于L形瓦参数设计提出一种通用的有向双环网络最优路由算法.该算法适用于单位步长和非单位步长有向双环网络.仿真结果表明,与基于[+h]边优先路由及基于二叉树的最优路由算法相比,该算法无需建造竹筏及二叉树的空间,执行效率明显提高.     

Consensus Of Identical Linear Systems with Communication Delays by Using the Information of Second‐Order Neighbors

This paper studies the consensus protocol using the information of second‐order neighbors in undirected and connected networks of linear systems with communication delays. The feedback matrix which guarantees consensus under both the proposed and the traditional protocol is given; it is shown that with this matrix, the networks under the proposed protocol converge faster than the traditional protocol. Based on this result, the delay sensitivity of the proposed protocol is considered under an assumption about the communication topology. The maximum allowable upper bound of the delays is obtained by solving certain linear matrix inequalities. Two simulation examples are presented to illustrate the effectiveness of the theoretical results.     

一类新的层次双环网络及其最优路由算法

用图的笛卡尔积Fm×Fm-1×…×F1×G构造一类新的层次双环网络,给出其最优路由算法。图G为Petersen图,Fi为特殊的无向双环网络。研究网络的一些基本性质,并与杜艳等构造的层次双环网络(计算机工程与应用,2010年,第34期)进行比较。分析结果表明,新构造的网络是一类接连度小、直径短,存在简单且路由算法最优的新型网络拓扑结构。     

Accelerating average consensus by using the information of second-order neighbours with communication delays

This article investigates the problem of accelerating average consensus in undirected and connected networks. The protocol using the information of second-order neighbours with communication delays is proposed and the delay effects on stability and the convergence speed are analysed, respectively, under an assumption about the network topologies. It is proved that, for appropriate communication delays, networks reach average consensus faster under the proposed protocol than the standard protocol using only the information of first-order neighbours. Finally, a simulation example is presented to illustrate the proposed results.     

一些新的紧优与次紧优无向双环网络无限族

无向双环网络是有n个结点的度为4的循环图。它是计算机互连网络的一类重要拓扑结构,广泛应用于计算机局域网和各种并行处理结构。给出一些新的带参数的紧优与次紧优无向双环网络无限族。     

Sampled-data based distributed convex optimization with event-triggered communication

This paper studies the distributed convex optimization problem for multi-agent systems over undirected and connected networks. Motivated by practical considerations, we propose a new distributed optimization algorithm with event-triggered communication. The proposed event detection is decentralized, sampled-data and not requires periodic communications among agents to calculate the threshold. Based on Lyapunov approaches, we show that the proposed algorithm is asymptotically converge to the unknown optimizer if the design parameters are chosen properly. We also give an upper bound on the convergence rate. Finally, we illustrate the effectiveness of the proposed algorithm by a numerical simulation.     

离散高阶分布式一致性算法

为了提高分布式一致性算法的收敛速度, 提出了一种离散高阶分布式一致性算法。该算法通过单跳通信, 利用二跳邻接节点的前多步信息来加速分布式一致性算法的收敛速度。对无向通信拓扑下该算法的收敛性能和收敛速度, 以及带通信延时的该算法的收敛性能进行了分析和仿真比较, 结果显示, 该算法在满足条件下能收敛到初始状态的平均值, 与同样利用二跳邻接节点信息的算法相比, 具有通信量小, 收敛速度更快的特点, 但是能容忍的通信延时变小。     

Consensus of feedforward nonlinear systems with a time-varying communication delay

The consensus problem of feedforward nonlinear systems under an undirected network with a time-varying communication delay is studied. In order to solve this problem, new consensus controller with an additional design parameter that can eliminate the effect of a feedforward nonlinearity and a time-varying communication delay on the consensus problem is proposed. Also, it is proved that if an upper bound of time-varying delay is known, the proposed consensus controller can always solve the consensus problem of multi-agent systems even in the presence of feedforward nonlinearity and an arbitrarily large communication delay. A numerical example is given to illustrate the validness of the proposed approach.     

Average Convergence for Directed & Undirected Graphs in Distributed Systems

Consensus control of multi-agent systems is an innovative paradigm for the development of intelligent distributed systems. This has fascinated numerous scientific groups for their promising applications as they have the freedom to achieve their local and global goals and make their own decisions. Network communication topologies based on graph and matrix theory are widely used in a various real-time applications ranging from software agents to robotics. Therefore, while sustaining the significance of both directed and undirected graphs, this research emphases on the demonstration of a distributed average consensus algorithm. It uses the harmonic mean in the domain of multi-agent systems with directed and undirected graphs under static topologies based on a control input scheme. The proposed agreement protocol focuses on achieving a constant consensus on directional and undirected graphs using the exchange of information between neighbors to update their status values and to be able to calculate the total number of agents that contribute to the communication network at the same time. The proposed method is implemented for the identical networks that are considered under the directional and non-directional communication links. Two different scenarios are simulated and it is concluded that the undirected approach has an advantage over directed graph communication in terms of processing time and the total number of iterations required to achieve convergence. The same network parameters are introduced for both orientations of the communication graphs. In addition, the results of the simulation and the calculation of various matrices are provided at the end to validate the effectiveness of the proposed algorithm to achieve consensus.