1,720,960 research outputs found
Comparison of two sealing coupling geometries for a direct fuel injector
No full textThe present paper describes some Finite Elements simulations carried out in order to investigate the contact problem in the sealing region of a direct fuel injector. In particular two different design solutions have been analyzed, both patent pending, one characterized by a conformal contact of two conic surfaces and the other one by a non-conformal contact between a cone and a sphere. Pressure distribution, contact width and von Mises equivalent stress have been calculated and employed as comparison parameters. Two different loading conditions have been considered: nominal loads and nominal loads plus undesired effects. Also deviations from the nominal geometry, obtained from profile detection of 40 samples, have been introduced for considering a real-like case. Numerical results stress the robustness of the non-conformal solution with respect to geometrical tolerances and real loading conditions
Analisi delle soluzioni tecniche attualmente allo studio nei programmi di ricerca Europei e degli Stati Uniti per i reattori a confinamento magnetico, alla luce degli ultimi sviluppi relativi alla riduzione delle dimensioni del progetto ITER
No full textNumerical multilevel investigation for evaluation of pressure distribution in EHL circular contacts from film thickness measurements
No full textIn this paper an analysis of the Elastohydrodynamic lubricated circular contact through a hybrid technique is presented. In particular the attention is focused on the pressure distribution calculation. A versatile code has been developed, able to evaluate the pressure distribution starting from 3-D film thickness maps obtained from the analysis of the interferometric images. The code is developed in C++ and is based on Multigrid Technique. This hybrid technique has a basic advantage with respect to the full numerical approach: the pressure is obtained without making any assumption about the lubricant itself. The main disadvantage of the method is that high resolution of the interferometric images is requested
Evaluation of Air/Cavitation Interaction Inside a Vane Pump
No full textGenerally, in a positive displacement pump, cavitation can occur when the fluid pressure falls under the vapour pressure at the operating conditions. This phenomena leads to the generation of vapour bubble dispersed inside the flow.
In fluid power application, cavitation is mostly detrimental because the vapour bubbles could be transported by the fluid toward the high pressure zones inside the pump causing their implosion and hence shock waves. When these shock waves are sufficiently close to the pump walls their physical action on the walls appears as a surface mechanic erosion.
Direct detection of cavitation is quite impossible because of the difficulties in positioning experimental sensors inside the fluid power components. To overcome this problem a valid alternative approach could be represented by the Computational Fluid Dynamic (CFD) tools.
In this paper the CFD analysis of a vane pump is presented. All the 3D simulations were performed using Fluent V12. In particular, the pump analysis was focused on the generation and evolution of the cavitation phenomena inside the machine to identify the locations where this phenomena can occur. Moreover, the influence of incondensable gas dissolved inside the fluid operator on both pump performance and cavitation evolution was evaluated. Significant results were obtained about the influence of expansion/compression of non-condensable gas on the cavitation evolution.
The adopted approach is generic in nature, and the obtained results can be easily use to optimise other pump designs as well
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
Analysis of Air/Cavitation Interaction Inside a Rotary Vane Pump for Application on Heavy Duty Engine
No full textThis paper deals with a CFD three-dimensional multiphase simulation of rotary vane pump.
The paper presents a suitable methodology for the investigation of the cavitation effects and/or incondensable gases. All the 3D simulations were performed by using Fluent v12 (Beta version). A moving mesh methodology was defined to reproduce the change-in-time shape of the internal pump volumes. In particular, the pump analysis was focused on the generation, and evolution of the cavitation phenomena inside the machine to identify the locations where these phenomena could occur. Moreover, the influence of incondensable gas dissolved inside the operator fluid on both pump performance and cavitation evolution was evaluated. Significant results were obtained about the analysis of incondensable gas influence on the cavitation evolution showing that, today, CFD analysis can provide detailed information on such harmful phenomena which cannot be achieved by experiments.
The approach adopted is generic in nature, and the obtained results can be easily used to optimize other pump designs
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
Experimental and Theoretical Results on the CRTM Plain Journal Bearings up to Extreme Working Conditions
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