1,720,958 research outputs found
3D CFD Transient Analysis of the Forces Acting on the Spool of a Directional Valve
No full textIn this paper, a study of a hydraulic directional valve using a tridimensional fluid-dynamic approach will be shown. During the valve spool displacement, the fluid-dynamics inside the valve creates forces who could reduce the valve performance. The adopted methodology allowed the valve designer to study the complex fluid-dynamic behavior inside the valve and greatly help them to design the internal geometry with the objective of improving the valve performance. This paper shows how a tridimensional fluid-dynamic approach can help engineers to develop the best valve geometry reducing the prototyping requirement and finally the time-to-market and, consequently, the development cost
3D Dynamic Simulation of a Flow Force Compensated Pressure Relief Valve
No full textThe paper deals with the 3D and 0D simulation of a conical popped pressure relief valve with flow force compensation. The commercial CFD code PumpLinx® was used to create a dynamic model of the valve and the interaction between the poppet dynamics and pressure field was taken into
account. The model is able to determine the equilibrium position of the poppet in order to estimate the regulated pressure as function of the flow rate. A good agreement with the experimental data was found in the evaluation of the effect of the flow force compensation. Once validated, the CFD code was used to study the influence of the deflector geometry on the opening force. Moreover it was also used for determining some
proper data to be supplied as input to a lumped parameters model of the valve. The tuning of the 0D model involved the discharge coefficient and the flow force. For the evaluation of the flow force compensation, a lookup table was calculated by the CFD code and then interpolated in the 0D model as function of the poppet displacement and of the flow rate
A Tridimensional CFD Analysis of the Oil Pump of an High Performance Motorbike Engine
No full textThe main target of nowadays engine designers is to focus on exhaust emissions, fuel consumption and engine performance, so during the design phase of a new internal combustion engine, all the aspects related to friction and mechanical power loss must be deeply considered. And then, also the friction related to engine lubrication system must be analyzed and studied. In this paper a tridimensional CFD analysis of the lubrication circuit oil pump of a modern high-performance engine manufactured by Aprilia will be shown. The model was build up with PumpLinx®, a commercial CFD 3D code by Simerics Inc.®, taking into account all the phenomena associated to the fluid cavitation. The model was validated by data of an experimental campaign performed on a hydraulic test bench, at the Industrial Engineering Department of the University of Naples, Federico II
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
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