Consensus tracking control for sampled-data second-order multi-agent systems with arbitrary weights under fixed communication topology

This paper focuses on the consensus tracking control problem of multi-agent systems (MASs) with arbitrary adjacency weights instead of traditional nonnegative weights in a sampling setting. First, unlike Lemma 4 in Hu and Hong [2007. Leader-following coordination of MASs with coupling time delays. Physica A: Statistical Mechanics and its Applications, 374(2), 853–863], for MASs with arbitrary weights, the global reachability of the leader node is just a necessary but not a necessary and sufficient condition to guarantee the positive stability of matrix H. Hence, it's urgent for us to establish some positive stability criteria of matrix H first, which is a necessary condition for MASs to achieve consensus tracking. Simultaneously, we also solve the following problems successfully: which nodes should have direct connection with the leader? What's the range size of the leader adjacency coefficients? Then, some sufficient consensus tracking control conditions are obtained for MASs without time-delays and with time-delays by using matrix analysis method and perturbation theory, respectively. Finally, numerical examples are given to illustrate the effectiveness of our results.     

Edge consensus on complex networks: a structural analysis

This paper investigates the consensus taking place on the edges of networks by defining dynamics to edges. Discrete-time and continuous-time edge consensus protocols are proposed in which each edge regulates itself according to the information of itself and its neighbouring edges. By mapping the original graph to its corresponding line graph, conditions guarantee the reaching of edge consensus are presented. Furthermore, the influence of network structure on the speed of reaching edge consensus is analysed by considering a scale-free network with a tunable exponent γ between 2 and ∞. It is found that the convergence speed increases as the network becomes more heterogeneous. In addition, as original network becomes more homogeneous, i.e. as the exponent γ increases from 2, the corresponding line graph becomes more heterogeneous till γ reaches 2.5, after that, the line graph becomes more homogeneous.     

Beyond Le Corbusier and the modernist city: reframing Chandigarh's ‘World Heritage’ legacy

Mounting concern about the slow progress of the drive to reconstruct Britain's cities in the late 1940s and 1950s led to a sustained debate about strategies and priorities. This paper offers insight into the climate of ideas of a key period in the recent past by considering the work of the Society for the Promotion of Urban Renewal (SPUR). A pressure group that campaigned for resuscitation of urban reconstruction under the banner of ‘urban renewal’, SPUR staged exhibitions and published manifestoes that reasserted core urban values, reconfigured decentralization on an intraurban basis, proposed multi-level circulation systems and, latterly, sought to redress the balance of rehabilitation and conservation strategies against comprehensive redevelopment. After a contextual introduction, the opening section of this paper clarifies two key concepts – ‘reconstruction’ and ‘renewal’ – that shaped thinking about the replanning of British cities in the early postwar period. The ensuing sections analyse the origins and founding ideals of SPUR and examine its key projects and manifestoes. The conclusion reflects on consensus and plurality in the group's work in the context of wider currents of thought about urban renewal.     

更好运用标准 构建公平规范的市场秩序

Standards serve as a fundamental system for market order regulation. The theme of 2014 World Standards Day is ＂Standards level the playing field＂. It has become a global consensus that standards are used to regulate market order and facilitate market unification. To enhance the reform and opening policy thoroughly and promote China＇s economy to a higher level, it is required to attach more importance to the standards construction and make best use of standardization.     

模拟人群信任和决策机制的协作频谱感知方法

通过模拟人群内部的信任和决策机制,针对多用户的频谱协作感知一致性问题,提出了一种分布式算法。该算法首先通过网络的历次协作过程预测出各感知用户的动态可信值,据此产生用户的相对可信值,并结合决策机制使得用户之间进行数据交互,随着数据的可信、迭代交互,所有用户状态将趋于一致,最后通过判定算法得出最终结果。算法充分考虑了实际环境中各用户频带感知能力的不平衡性,而且各次级用户只需要进行少量局部数据交换即可实现协作感知,与传统的OR-rule、1-out-of-N rule以及普通迭代法有较大区别。对3种数据篡改攻击进行了分析,并在预测算法的基础上提出了相应的安全策略。理论分析与仿真结果表明,新算法在准确性和安全性上均优于传统合作频谱感知算法,能显著提高频谱感知准确率,同时兼具较强的防攻击能力。     

多无人机任务集结合作博弈优化自组织协同控制

基于一致性理论的多无人机系统自组织协同作战是未来无人机应对突发任务的重要方式,任务集结是协同作战的首要行动和自组织协同控制的重要内容。为优化集结行动中系统任务状态协调过程能量最优性、协同控制动态响应性和集结行动时效性3个性能指标,采用基于快速一致性控制算法的协同控制结构,在合作博弈框架下给出多无人机系统自组织协同与优化控制问题描述,建立了优化控制输入的Pareto解集,采用Nash讨价还价方法给出基本合作博弈优化一致性控制算法。在基本算法中引入过去状态差值,并以优化目标构建适应度函数,采用遗传算法优化代价函数的加权矩阵,得到改进合作博弈优化一致性控制算法。理论分析和仿真实验验证了方法的可行性和有效性。     

基于 RANSAC 的视觉里程计优化方法研究

针对图像特征产生误匹配影响基础矩阵计算,导致同步定位与地图构建(SLAM)视觉里程计估计精度差的问题,提出一种基于随机抽样一致(RANSAC)的视觉里程计优化方法。该方法首先通过最小距离阈值法对初始匹配集粗滤除,再采用RANSAC计算图像间相对变换关系,若符合变换关系为内点,内点数最多的迭代结果为正确匹配结果;然后计算图像间单应变换并利用其计算基础矩阵,采用对极几何约束确定内点,得到具有最多内点的基础矩阵;最后采用TUM数据集从特征匹配与基础矩阵计算两方面进行优化算法效果验证。结果表明,该算法可提高运行效率且有效去除误匹配特征点,使匹配正确率提高7.7%,基础矩阵估计算法在提高基础矩阵计算精度的同时,内点率也提高了3%,算法为提高视觉里程计精度估计精度提供了理论基础。     

含分布式光伏和电动汽车的主动配电网电压一致性协同控制

分布式电源渗透率的快速增加使得低压配电网中出现严重的电压问题,而电动汽车(Electric Vehicle,EV)的广泛应用使得其参与电压控制成为了可能。提出了一种利用电动汽车的电池能量管理和分布式光伏阵列的无功、有功控制,来调节光伏发电渗透率较高的配电网中的电压。考虑到电动汽车电池容量和荷电状态(SoC)的不同,提出基于一致性算法的分布式控制策略来有效利用EV电池的有限存储容量。在此基础上,提出基于分布式光伏组件无功调节和有功调节的本地电压控制策略,并计算分布式光伏的无功与有功控制调节量。通过仿真分析,验证了文中所提的分布式一致性电压协同控制的有效性,可以有效缓解由反向潮流引起的电压升高,并补偿峰值负载导致的电压降落,消除由分布式电源大量接入带来的电压越限问题。     

分布式存储系统读写一致性算法性能优化研究综述

读写一致性算法被广泛部署到分布式存储系统,以保证读写数据的正确性.然而,读写一致性算法通常需要使用一个复杂的通信协议来保证多个节点读写数据的正确性,会带来较大网络传输开销和读写时延.由于各种读写一致性算法实现机制存在较大差异,特定的读写一致性算法往往需要部署到特定的存储应用场景,才能高效地执行数据读写操作,保障对其上应...     

Automated Fast Initial Guess in Digital Image Correlation

A challenging task that has hampered the fully automatic processing of the digital image correlation (DIC) technique is the initial guess when large deformation and rotation are present. In this paper, a robust scheme combining the concepts of a scale‐invariant feature transform (SIFT) algorithm and an improved random sample consensus (iRANSAC) algorithm is employed to conduct an automated fast initial guess for the DIC technique. The scale‐invariant feature transform algorithm can detect a certain number of matching points from two images even though the corresponding deformation and rotation are large or the images have periodic and identical patterns. After removing the wrong matches with the improved random sample consensus algorithm, the three pairs of closest and non‐collinear matching points serve for the purpose of initial guess calculation. The validity of the technique is demonstrated by both computer simulation and real experiment.