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Atmospheric Research with the Small Expendable Deployer System: Preliminary Analysis
No full textData on the structure of the lower thermosphere are extremely limited because of the inaccessibility of this region to research vehicles. Downward-deployed tethered satellites can provide access to this region of the atmosphere. A preliminary analysis of the potential use of the end mass of the Small Expendable Deployer System as a scientific platform for atmospheric and aerothermodynamic research is presented. To this end, the deployment and attitude dynamics of the end mass during the first mission have been numerically simulated. It is shown that measurements of the atmospheric mean density with the end-mass onboard accelerometers can be performed only in a short time interval around the orbit perigee; in addition, the analysis of the payload attitude dynamics shows the need for attitude control. A preliminary analysis of end-mass attitude control techniques is then performed. Results show that the stringent attitude control requirements can be satisfied by active control device
Attitude Dynamics of the Small Expendable-Tether Deployment System
No full textThe Small Expendable-Tether Deployment System (SEDS) provides a low-cost facility for deploying tethered payloads in space. Among various objectives, SEDS' first flight will assess the capability of tethered platforms to carry out measurements in the upper atmosphere. The performance of onboard instruments is seriously affected by the payload's attitude dynamics. In this paper, SEDS' attitude dynamics and stability are analytically and numerically analysed for the nominal mission. It is shown that although a passive damper can be used to reduce the amplitudes of the attitude angles, appropriate control techniques are required for scientific instrumented platforms
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Analysis of effects of initial conditions and physical parameters in a differential accelerometer modeled as a multibody system
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Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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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