1,720,978 research outputs found
PAYLOAD ORBITAL SEPARATION AND POLLUTION ANALYSIS TOOL FOR CLUSTER LAUNCHES OF SMALL SATELLITES
No full textOn February 13th, 2012, at 10:00 UTC, the VEGA VV-01 launch was carried out from the European spaceport in Kourou, French Guyana. A scientific payload named LARES (LAser RElativity Satellite) was released as the main payload and the microsatellite ALMASat-1 (a 30cm cube weighing 13.5 kg) provided by the II Faculty of Engineering of the University of Bologna and 7 Cubesat selected by ESA’s Education Office, were also included as secondary payloads and released by the VEGA Maiden Flight.
The payload composition foresaw the release of the main payload LARES along a circular 1450x1450 orbit, while the secondary payloads will be released along an elliptic deorbiting trajectory, within a time interval of 30 seconds between the passivation of the upper stage and the depletion of the possibly contaminating liquids and gases from the AVUM.
Motivated by this very challenging mission, the ALMASat-1 team in collaboration with ALMASpace S.r.l. developed a simulation Tool for sHort and medium ORbital propagation (THOR) to carry out an analysis of payloads separation & orbit propagation for investigating possible payload collisions and pollution-contaminations. The propagation part of the simulation tool has been validated by using an ESOC space debris office propagation tool based on the propagator of the Orbit Determination via Improved Normal Equations (ODIN) software package
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
Analysis of Inter-Satellite Communication Protocols and their Effects on Satellite Formation Control
No full textSatellite Formation Flying (SFF) enables the collective use of multiple spacecraft to perform the function of a single, large, virtual instrument. Formation Flying missions involve the tracking and maintenance of spacecraft in a desired geometric configuration, requiring to the distributed spacecraft to exert collaborative control of their mutual positions and orientations. The mutual nearness of spacecraft in controlled formation requires inter-satellite communication to exchange position and orientation information and to pass thruster actuation commands. In particular, attitude and orbital manoeuvre algorithms must ensure the minimum delay in performing the control of the formation geometry. As a consequence, one of the main challenges in such a mission is to design the appropriate communication protocol that accommodates a high communication reliability together with the minimum delay in a simplified hardware
ALMASat-EO Attitude Determination Algorithms: Evaluation, Implementation And Numerical Simulation
No full textThe on-board attitude estimation represents a major task of the attitude and orbit determination and control subsystem as it is necessary to guarantee the spacecraft pointing accuracy as prescribed by the mission requirements. In a space mission each components requires a deep test campaign as well as the attitude estimation techniques where the Monte Carlo statistical approach represents the final step to fully validate the attitude determination algorithms. Motivated by this needs, a simulation tool suitable to develop, test and finally validate all the algorithms selected for the mission has been conceived and implemented in the ALMASat-EO context
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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