1,720,969 research outputs found
Thermite-for-Demise (T4D): Charge Shaping Exploratory Tests
No full textThermite-for-Demise (T4D) is an innovative approach to aid spacecraft demise during re-entry by leveraging thermite-based materials to enhance structural demisability. This study investigates the initial steps in developing thermite-based materials tailored for Design-for-Demise (D4D) applications. Two fabrication techniques were explored: pelletization of thermite powders with or without polymeric binders and embedding thermite in a polymer matrix for casting. The pelletization of fuel rich thermite formulations, with the addition of polymeric binders resulted in lower porosity. However, compression tests revealed the mechanical limitations and variability of the produced pellets, emphasizing the necessity for further processing to improve the mechanical performances. Thermite dispersion in acrylonitrile butadiene styrene (ABS) demonstrated promising pyrotechnic behavior at thermite concentrations equal or higher than 15%. This work establishes a foundation for future exploration of thermite-based structural reactive materials to mitigate ground casualty risks due to spacecraft uncontrolled re-entry
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
Thermite-for-demise (T4D): experiments and numerical modelling on solar array drive mechanism mock-ups containing thermite in an arc-heated wind tunnel
Full text linkThe ESA-TRP SPADEXO project investigated the use of thermites to provide additional enthalpy to a spacecraft re-entering towards the Earth, with the objective of limiting its casualty risk on ground. Steel mock-ups inspired by the geometry of solar array drive mechanisms were filled with thermite and placed in DLR’s L2K arc-heated hypersonic wind tunnel. In each of these samples, a set of thermocouples was installed to monitor ignition and propagation of the heat generated by the reaction. One of the thermocouples was placed in a hole machined inside the mock-up wall to monitor temperature evolution in proximity of the pyrotechnic charge, without the risk of losing the sensor due to the ignition of the thermite. The main objective of these tests was to study the dependence of the heat transferred from the internal charge to the surrounding structure from the filling level. Results showed that higher thermite filling resulted in higher transferred enthalpy. In the presence of a large thermite amount, the reaction led to the formation of a dense liquid drop close to the side wall, causing significant heat transfer towards the wall of the mock-up. Tests were rebuilt using the SCARAB re-entry software, extended with a dedicated model to represent the ignition of an internal charge. Ignition and heat transfer were adequately described by the model in most of the test configurations. Specific parameter tuning was needed for the highest filling factor tested in this work, highlighting the influence of reaction products internal dynamics on the heat transfer processes
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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