1,720,956 research outputs found
Micro-heat-sinks for space applications
No full textDuring the space missions, the problems related to the thermal conditioning of devices, to the personnel comfort and to the thermo-mechanical stresses are known and important. Furthermore for a space mission certain priorities are stressed, such as the small dimension and the lightness of thermal equipments. Due to the presence of high temperature gradients, which straightforwardly implies significant heating/cooling powers, these characteristics are sometimes difficult to obtain. The decreasing of the satellites payloads in terms of mass and volume has brought to the necessity of a further development of traditional space technologies, such as heat pipes and radiators. A promising technology is the fabrication of micro-heat-sinks for active and passive thermal control systems suitable for the space environment, which is always an important workshop for future progresses. In fact, miniaturized heat sinks will have a terrestrial large industrial diffusion for electronic component cooling, in propulsion and in the power production for satellites, spacecrafts and airplanes, in various biomedical applications and in cloth conditioning in harsh environmental conditions. The present paper intends to introduce the reader to the standard space requirements, to present some new prospective and experimental results and to discuss the use of thermal MEMS for micro- and nano-satellites
Global characterization of innovative polymeric micro-heat sink
No full textDuring the space missions, the problems related to the thermal conditioning of devices, to the personnel comfort and to the thermomechanical stresses are known and important. Furthermore for a space mission certain priorities are stressed, such as the small dimension and the lightness of thermal equipments. Due to the presence of high temperature gradients, which straightforwardly implies significant heating/cooling powers, these characteristics are sometimes difficult to obtain. Besides, miniaturized heat exchangers will have a terrestrial large industrial diffusion for electronic component cooling, in propulsion and in the power production for microsatellites, spacecrafts and airplanes and in many biomedical applications, for example, in cloth conditioning in harsh environmental conditions. Given the great value of the ratio between exchanging surface and volume of these systems, the specific thermal power per unit volume can reach extremely high values (1000 kW/m2 is a possible target). The low density, high elasticity and mechanical resistance suggest that the development of a new technology for heat sink, based on a sheet of polymeric microtubes (with a overall thickness of some tenths of millimeter) could be of great interest for space and terrestrial applications. A polymeric micro-heat sink was designed and built. Many technical problems were solved and a first prototype is available. The micro-heat sink was configured to cool an electric resistance with nitrogen and helium. An experimental set-up was built and some preliminary tests are running. For gas flow rates ranging from 3 to 26 Nl/min, a maximum heat flux of about 14 kW/m2 has been reached. The heat-sink has a surface of 6cm2 and a weight of 0.25g. The maximum pressure drop reached 3 bar. Different polymers were considered in order to test the heat sink thermal and mechanical resistances
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
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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