1,721,161 research outputs found
A Distributed Design and Plug-n-Play Algorithm for Consensus of Constrained Networks
No full textIn recent years, significant attention has been devoted to consensus protocols for Multi Agent Systems (MASs). Some of the approaches in the literature design protocol gains and/or coupling strength parameters, requiring global information about the communication topology (e.g., network Laplacian eigenvalues). Other methods circumvent this limitation by adaptively tuning the coupling strengths among network nodes. Nevertheless, such schemes may not work in constrained network scenarios where nodes' coupling strengths and degrees are subject to specific bounds. In this letter we propose a distributed design algorithm to assess leader-follower consensus of direct constrained networks. Additionally, the proposed algorithm has the remarkable feature that addition or removal of an agent (i.e., plug-n-play operation) requires, at most, the controller design of the only agent and an update for the influenced neighbors. A representative numerical example demonstrates the effectiveness of the proposed algorithm
On consensus protocols allowing joint-agent interactions
Full text linkIn this note we consider consensus protocols where an agent would not be influenced by any of his neighbours singularly taken, but might be sensitive to the simultaneous and coherent influence of two or more of them. This may resemble several common behaviours in social, economic and opinion networks (i.e. conformity, risk aversion, social inertia, herding). We derive novel graph-theoretical concepts to describe and analyze the ability of general networks with joint-agent interactions to converge towards consensus. Interestingly, and for the first time, we borrow to this end the language of Petri Nets as a convenient way to describe bipartite directed graphs, showing how the notion of siphon is helpful in characterizing the flow of information across the network and its ability to induce attainment of consensus among agents in the considered set-up
Global stability of multi-agent systems with heterogeneous transmission and perception functions
Full text linkOn adversary robust consensus protocols through joint-agent interactions
No full textA generalized family of adversary robust consensus protocols is proposed and analyzed. These are distributed algorithms for multiagent systems seeking to agree on a common value of a shared variable, even in the presence of faulty or malicious agents, which are updating their local state according to the protocol rules. In particular, we adopt monotone joint-agent interactions, a very general mechanism for processing locally available information and allowing cross-comparisons between state-values of multiple agents simultaneously. The salient features of the proposed class of algorithms are abstracted as a Petri net and convergence criteria for the resulting time evolutions formulated by employing structural invariants of the net
Design and experimental testing of an optimization-based flow control algorithm for Energy Harvesting Wireless Sensor Networks
No full textIn this paper a distributed flow control law is proposed to maximize throughput and to minimize energy consumption in Energy Harvesting Wireless Sensor Networks (EH-WSNs). We preliminary recast the control problem in terms of primal–dual optimization one taking into account the bandwidth and energy autonomy node constraint. Then, we devise a distributed flow rate control implemented at each node that allows the overall network to converge to the optimal solution of the original problem. The closed loop EH-WSN stability and convergence to the optimal equilibrium are proven. The effectiveness of the proposed control law in terms of throughput and network lifetime performance is experimentally validated by a small representative EH-WSN. The experimental results are in a good agreement with the theoretical ones
Consensus-based algorithm for distributed estimation of the maximum of a field
Full text linkThis paper deals with the problem of distributed estimation of the maximum of a continuous scalar field by combining exhaustive ergodic search with multi-agent consensus protocols. In this original set-up, the presence of unilateral interactions and exogenous signals is considered, the latter representing the measures sampled by the agents and an algorithm is devised to estimate the maximum of the field over the domain spanned by the agents. Necessary and sufficient conditions are given to guarantee convergence to the maximum field value. Illustrative examples are presented to show the effectiveness of the proposed framework and conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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