1,720,966 research outputs found
Studio di un motore a due tempi ad accensione comandata di concezione innovativa
No full textL’Aquila, 14 – 17 Settembr
Studio di un motore a due tempi ad accensione comandata di concezione innovativa
No full textL’Aquila, 14 – 17 Settembr
Experimental investigation of a multiple disk centrifugal pump
No full textThe work presents an experimental investigation of the characteristics of a centrifugal pump equipped with a multiple disks rotor specifically designed to operate in the optimal flow regimes. Global measurements are carried out with controlled accuracy while the machine is processing an highly viscous Newtonian lubricating oil in a closed loop system. Results, presented in non dimensional form, indicate that the work transfer is truly efficient, and leads to stable flow conditions all across the performance map. Rotor efficiencies in excess to 80% are measured in a wide range of flow coefficients, thus demonstrating that the theoretical achievements of the late 70s pertaining to the single pair of co-rotating disks can be attained in a true machine environment, provided the optimal wheel flow conditions are preserved. Overall pump efficiency is penalized by inadequate diffusion systems, and not by rotor work transferring mechanisms
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
Steady and unsteady experimental analysis of a turbocharger for automotive applications
No full textThe paper describes the steady and unsteady performance characteristics of a small size turbocharger typically employed in automotive downsized engine applications. The analysis is carried out by experimental means using an innovative hot gas generator system specifically designed for turbocharger testing which is capable of delivering a wide range of flow rates with adequate thermodynamic characteristics. More in detail, the gas generator consists of a medium size direct injection compression ignition Internal Combustion Engine (ICE) feeding the turbine of the test article. To independently set the hot gas mass flow rate and the turbine inlet temperature, the operating parameters of the aforementioned ICE are specified through an electronic control unit in a fully automated manner. Compared to previously presented data [1] (Energy Procedia, vol. 45, pp 1116-1125, 2014), those reported herein have been collected with the help of newly installed equipment and controlling software allowing for the estimation of the thermal power transferred from the turbocharger to the environment. In particular, thanks to a first law analysis, the collected measurements have shown that the algebraic sum of the thermal power transferred to the lubricating oil as well as to the environment is roughly speaking 20-30% of the compressor total enthalpy change per unit time. Moreover, it has been shown that evaluating the compressor efficiency through classical expression based on the adiabatic assumption leads to a 5-10% relative error. The improved experimental set up also allows for higher precision transient analysis both on the cold and hot side branch of the test article. While the steady-state performance maps of the turbocharger are readily obtained with the semi-automated testing procedure, the detailed analysis of the unsteady phenomena related for instance to the occurrence of mild and deep compressor surge events, are reproduced and thoroughly analysed using the rig in more advanced operating mode
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
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