1,721,090 research outputs found
Controllability analysis of multi-agent systems using relaxed equitable partitions
Full text linkThis paper investigates how to make decentralised networks,
amenable to external control, i.e., how to ensure that they are
appropriately organised so that they can be effectively ‘reprogrammed’.
In particular, we study networked systems whose interaction dynamics
are given by a nearest-neighbour averaging rule, with one leader node
providing the control input to the entire system. The main result is a
necessary and sufficient condition for the controllability of such systems
in terms of the graph topology. In particular, we give a graph theoretic
interpretation of the controllability properties through the so-called
relaxed equitable partition
Rendezvous with Multiple, Intermittent Leaders.
No full textIn this paper we study bipartite, first order- networks where the nodes take on leader or follower roles. In particular, we let the leaders’ positions be static and assume that they are only intermittently visible to the followers. This is an assumption that is inspired by the way female silkworm moths only intermittently release pheromones to be detected by the males. The main result in this paper states that if the followers execute the linear agreement protocol, they will converge to the convex hull spanned by the leaders (may they be visible or not)
Hierarchical Containment Control in Heterogeneous Mobile Networks
No full textIn this paper, the multi-agent containment problem is investigated. In particular, we focus our efforts on a continuation of our previous work on leader-follower networks, by imposing a hierarchical structure on the network topology. The main idea is to organize the team of autonomous, mobile agents in a multi-layered structure, which enables us to understand the tradeoffs between performance and complexity of the hierarchical topology, and we achieve this in the setting where we drive the collection of mobile agents to a target location while guaranteeing containment. In other words, the movement should be such that each layer stays within the convex hull of its parent layer while keeping its child layer inside its own convex hull. Such a criteria is to ensure that the movement of all the agents is constrained to a limited area while the group is moving. The application of this arises, for example, in surveillance, demining, and hazardous materials removing
Containment Control in Mobile Networks
No full textIn this paper, the problem of driving a collection of mobile robots to a given target destination is studied. In particular, we are interested in achieving this transfer in an orderly manner so as to ensure that the agents remain in the convex polytope spanned by the leader-agents, while the remaining agents, only employ local interaction rules. To this aim we exploit the theory of partial difference equations and propose hybrid control schemes based on stop-go rules for the leader-agents. Non-Zenoness, liveness and convergence of the resluting system are also analyzed
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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