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Reliable Numerical Approach for a Design of an Inflatable Moon/Mars Habitat based on Material Tests in the SAS Simulator
No full textOptical sensor system applicability for spacecraft tests
No full textThales Alenia Space Italy - Rome is carrying out a program of research and development in the field of optical sensors in order to verify its applicability in aerospace. Within this program particular emphasis has been placed on a type of optical sensor called Fiber Bragg Grating sensor (FBG). In the last decade the use of this technology in many fields worldwide has highlighted the characteristics and properties which can also be applied in the field of satellite telecommunications. For the sake of experimentation three tests simulated in the IUAIT Thermal Facilities, which gave useful results to assess the possibilities of using the FBG sensor, were carried out. Copyright ©2010 by the International Astronautical Federation. All rights reserved
Degradation of the surfaces exposed to the space environment
Full text linkThe presence of several atomic species in the LEO (Low Earth Orbits) could be considered one of the reasons for the degradation of the surfaces exposed to the Space Environment. At an average height of 400 Km (the altitude of International Space Station), the concentration of the main atomic species during the high sun activity are: 1.5 x 10(9) cm(-3) for atomic oxygen (AO), 1.6 x 10(8) cm(-3) for molecular nitrogen (N-2) and 1.4 x 10(8) m(-3) for atomic nitrogen (N). The energy with which the atoms collide with the surface of orbiting vehicle depends on the relative speed of the vehicle itself. For instance, the atoms colliding the International Space Station (ISS) (orbit average height: 400 Km; relative speed: 7.5 Km/s) have an energy of 8 eV for N-2, 5 eV for OA and 4 eV for N. The atomic oxygen is the most abundant species presents in LEO and it is considered the main responsible of the thermal, optical and mechanical alteration of the surfaces exposed to the Space Environment. Different hypothesis are reported in literature in order to explain the physical/chemical mechanisms that govern the material degradation in the Space, but no conclusion has been reached. In the energy range of few of eV, the main mechanism with which colliding atoms transfer its energy to the atoms of the surface is by phonons. In this paper the effect of an oxygen ion beam produced in the space environment simulator on materials for Space applications is studied in the frame of the thermal spike theory. Comparison between the measured erosion and the calculated one will be reported. The erosion mechanism will be modelled in order to understand the main thermodynamic parameters that govern the interaction between the atomic oxygen and the surface of the tested materials. (c) 2006 Elsevier Ltd. All rights reserved
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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