1,720,955 research outputs found
Thermal and hydraulic performance of 3D printed jet impingement configuration for SiC power modules in aerospace propulsion inverters
No full textEfficiently controlling the temperature of power electronic inverters is crucial for aerospace applications with high power density. Effective thermal management strategies could enhance the power output of power inverters to their maximum rated capacity. Jet impingement is a promising technology with outstanding heat transfer characteristics, making it a sophisticated aid for cooling innovation in power inverters. A numerical comparative study was conducted between jet impingement and traditional pin finned heat sink. In our case study, the pin fin could not effectively regulate the junction temperature to a level below 150 °C. By using a 3D printed jet impingement housing composed of polymer, the weight of the power module thermal management system could be decreased by 71 % compared to a metallic pin finned heat sink. Moreover, this approach aids in lowering the junction temperature to 129 °C, under the same boundary conditions. Additionally, a numerical study was conducted on power modules with thermal imbalance used in aerospace inverters. The study proposed various configurations of jet impingement to reduce temperature differences between power module switches, as well as minimize the pressure drop across the jet impingement housing. The primary objective is to minimize the temperature disparity between the unbalanced switches in order to improve the overall reliability and lifespan of the power module, while decreasing the pressure drop. Among all the options, the optimum design achieves a minimal temperature difference of 24 °C between the power module switches, while the pressure drop reaches 12 kPa
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
Design of a Cylindrical Jet Impingement Cooling System for High-Power Common-Mode Choke in Aerospace Applications
No full textWith the increasing demand for efficient, power-dense, and reliable power systems in aerospace applications, the thermal management of high-power electronic components has become a critical challenge. High-power common-mode chokes, essential components for electromagnetic interference (EMI) suppression, generate significant heat during operation, necessitating effective cooling techniques to maintain optimal performance and prolong their lifespan. This paper presents the design of a novel cylindrical jet impingement cooling system specifically tailored for high-power common-mode chokes in aerospace applications. The proposed cooling system leverages the advantages of jet impingement cooling to achieve enhanced heat transfer and temperature uniformity across the magnetic core as well as the bus bar while offering a competitive mass reduction compared to similar devices. A cylindrical configuration is chosen to accommodate the geometric constraints of the magnetic core and bus bar configuration used in such applications. Mathematical modelling in partnership with computational fluid dynamics (CFD) simulations is employed to evaluate the thermal as well as pressure drop performance of the system
Numerical Investigation of Different Jet Impingement Configurations for Thermally Unbalanced Power Modules in Aerospace Traction Inverters
No full textThermal management of power electronic inverters becomes a critical necessity for high density aerospace applications. Proper thermal management techniques can push the rated power of such power inverters. Jet impingement is one of the optimistic techniques that possesses superior heat transfer characteristics, which can be an advanced assist for power inverters cooling innovation. This paper proposes different jet impingement configurations to provide a thermal management solution for thermally unbalanced power modules used in 1 MVA, 3-level ANPC inverter, by performing computational fluid dynamics simulations to analyze the thermal and hydraulic characteristics. The optimal design target is to decrease the temperature difference between the unbalanced switches to enhance the overall reliability and lifetime of the power module while simultaneously reducing the pressure drop. With the optimized design among all the proposals, the minimum temperature difference is 24 °C between the power module switches, while the pressure drop reached 12 kPa for the optimal jet configuration
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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