1,721,158 research outputs found
Erez Lieberman Aiden & Jean-Baptiste Michel - A Picture is Worth 500 Billion Words
No full text"[Google's digtized books] are very practical and extremely awesome." Erez Lieberman Aiden and Jean-Baptiste Michel from Harvard University use the 15 million books scanned and digitized by Google to show how a visual and quantitative analysis of text can provide insights about fields as diverse as lexicography, the evolution of grammar, collective memory, the adoption of technology, the pursuit of fame, censorship, and historical epidemiology. In the spirit of ideas worth spreading, TEDx is ..
Thermodynamic analysis of the Brayton-cycle gas turbine under equilibrium chemistry assumptions
Get PDFA design-point thermodynamic model of the Brayton-cycle gas-turbine
under assumptions of perfect chemical equilibrium is described.
This approach is novel to the best knowledge of the author.
The model uniquely derives an optimum work balance between power
turbine and nozzle as a function of flight conditions and propulsor
efficiency.
The model may easily be expanded to allow analysis and comparison of
arbitrary cycles using any combination of fuel and oxidizer.
The model allows the consideration of engines under a variety of
conditions, from sea level/static to >20 km altitude and flight Mach
numbers greater than 4.
Isentropic or polytropic turbomachinery component efficiency standards
may be used independently for compressor, gas generator turbine and
power turbine.
With a methodology based on the paper by M.V. Casey, “Accounting
for losses” (2007), and using Bridgman’s partial differentials , the
model uniquely describes the properties of a gas turbine solely by
reference to the properties of the gas mixture passing through the
engine.
Turbine cooling is modelled using a method put forward by Kurzke.
Turboshaft, turboprop, separate exhaust turbofan and turbojet engines
may be modelled. Where applicable, optimisation of the power turbine
and exhaust nozzle work split for flight conditions and component
performances is automatically undertaken.
The model is implemented via a VB.net code, which calculates
thermodynamic states and controls the NASA CEA code for the
calculation of thermodynamic properties at those states. Microsoft
Excel® is used as a graphical user interface.
It is explained that comprehensive design-point cycle analysis may
allow novel approaches to off-design analysis, including engine health
management, and that further development may allow the automation of
cycle design, possibly leading to the discovery of opportunities for
novel cycles
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
L’interprétation des graphiques produits par Ngram Viewer
No full textNgram Viewer est un nouvel outil mis en ligne par Google le 16 décembre 2010. Il permet de visualiser sous forme de graphiques les fréquences d’apparition de suites de mots dans les livres numérisés depuis 2003 sur Google Books. Ce projet a été initié en 2007 par un mathématicien et physicien américain, Erez Lieberman Aiden. Il a été soutenu par Google Labs et développé par des chercheurs de Harvard, en particulier Jean-Baptiste Michel, jeune polytechnicien français. L’application contient ac..
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
L'interprétation des graphiques produits par Ngram Viewer
No full textNgram Viewer est un nouvel outil mis en ligne par Google le 16 décembre dernier. Il permet de visualiser sous forme de graphiques les fréquences d'apparition de suites de mots dans les livres numérisés depuis 2003 sur Google Books. Ce projet a été initié en 2007 par un mathématicien et physicien américain, Erez Lieberman Aiden. Il a été soutenu par Google Labs et développé par des chercheurs de Harvard, en particulier Jean-Baptiste Michel, jeune polytechnicien français. Apparition et évoluti..
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