1,724,503 research outputs found
Behaviour-based circle formation control for a team of cooperative Unmanned Underwater Vehicles
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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
The ability of a weakly compressible solver to predict landing gear noise with flow-acoustic interactions
No full textThe ability of a weakly compressible solver to solve landing gear noise with flow-acousticcoupling is investigated. Traditionally compressible flow solvers are used to simulate flowacousticcoupling. However, compressible solvers require greater computational resourcescompared to incompressible solvers at low Mach numbers such as an aircraft on approachto landing. While incompressible solvers are able to capture the steady aerodynamics, in thiswork, their inability to capture the correct wall pressure spectra and far-field acoustics isdemonstrated for a relatively simple two wheel landing gear, i.e. the LAGOON (LandingGear Noise database for CAA validation) #1 geometry. This is due to the inability ofincompressible solvers to capture cavity resonances, which are important contributors tonot only tonal but also broadband noise. This is significant for landing gear noisepredictions. A weakly compressible solver is tested to determine its ability to resolve theflow-acoustic coupling for a low Mach number flow. This solver has a similar computationalcost to an incompressible solver. The simulations are performed using a weaklycompressible solver added to OpenFOAM with a one-equation Large-Eddy Simulationmodel. An incompressible simulation of the same configuration is also performed forcomparison. Results shows that the weakly compressible solver can correctly solve theresonant tonal and broadband noise that are absent in the solution from the incompressiblesolver. The weakly compressible solver maintains similar behaviour in predicting the timeaveragedand root-mean-square flow variables. A grid sensitivity study is also included, andconsistency is compared between the two meshes of different resolutions for both near-fieldpressure fluctuations and far-field acoustics. The computational cost of the weaklycompressible method for landing gear simulations is slightly less than the incompressiblesolver and significantly less than other fully compressible Navier-Stokes solvers
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
Behaviour-based rules with fuzzy logic controlled priority weights in multi-UUVs team cooperation
No full textA popular recent research trend is to investigate the feasibility of a team of cooperating UUVs (unmanned underwater vehicles). Animals group behaviour, such as fish schooling, may have lessons to offer the development of team cooperation. The goal of this paper is to justify the behaviour-based rules with fuzzy logic controlled priority weights works for team UUVs cooperation when considering dynamic manoeuvring models of an real UUV. The paper defines several behaviour-based rules to meet the requirement of a simple operational scenario. The steering angle factors generated from the rules are multiplied by the relative priority weight values and added together to make a decision on the desired vehicles' next steering angle. The priority weight values of rules are updated by the fuzzy logic method according to the situation that the vehicles meet in real time. In order to investigate the performance of the approach a dynamic manoeuvring model of a small UUV, SUBZERO III, is used to describe each vehicle in the team and a UUV cooperative mission scenario is assumed. The simulation results indicate that the entire system is successful in achieving the mission. Some parameters, such as vehicle velocity, motion update frequency, minimum distance between vehicles and minimum distance between vehicles and an obstacle, are discussed to prove that they must been specified in order to satisfy the mission requirements. From the results, we can conclude that the approach has potential for a real team of cooperative UUVs
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