1,720,954 research outputs found
Impact of different volume sizes on dynamic stability of a gas turbine-fuel cell hybrid system
No full textA dynamic model is developed for a microgas turbine (MGT), characterized by an intrinsic free-spool configuration, coupled to large volumes. This is inspired by an experimental facility at the National Energy Technology Laboratory (NETL) called hybrid performance (Hyper), which emulates a hybrid MGT and Fuel Cell system. The experiment and model can simulate stable and unstable operating conditions. The model is used to investigate the effects of different volumes on surge events, and to test possible strategies to safely avoid or recover from unstable compressor working conditions. The modeling approach is started from the Greitzer lumped parameter approach, and it has been improved with integration of empirical methods and simulated components to better match the real Hyper plant layout and performance. Pressure, flowrate, and frequency plots are shown for the surge behavior comparing two different volume sizes, for cases where gas turbine shaft speed is uncontrolled (open loop) and controlled (closed-loop). The ability to recover from a surge event is also demonstrated
Test Rig for Emulation of Turbocharged SOFC Plants
No full textThis work is devoted to an emulator test rig designed for experimental analysis on SOFC-based plants pressurised by a turbocharger. The utilization of a turbocharger for SOFC pressurization aims to reduce the machine costs, due to the large mass production of this component. This emulator rig is an essential plant to perform tests on the component integration, dynamic operations, control system development and prevention of risky operative conditions (e.g. surge). These are essential issues to be solved before developing expensive complete prototypes and the related commercialization. This experimental plant is based on a pressure vessel for emulating the thermal (combustor and inert ceramic material) and fluid dynamic (the volume) responses. The vessel pressurisation is obtained with a turbocharger, where the exhaust flow operating in the turbine powers the compressor. The plant is also equipped with a recuperator and with different valves for control and flexibility reasons (bleed, compressor/turbine bypass, and recuperator bypass). Preliminary experimental results are included in this work focusing attention on the turbocharger choice and on the component constraints. In details, these are the necessary experiments for choosing the suitable machine for the rig (with a good surge margin for this component coupling)
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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