1,721,151 research outputs found
Theoretical and experimental analysis on the thermal fluid dynamics of water droplets in irrigation
Full text linkA complete thermal fluid dynamics analysis of a sprinkler droplet following its path from the sprinkler nozzle to the ground is made difficult by the high nonlinearity of the differential equations describing the phenomenon. This fact, caused by a great inter-dependence between the parameters that play a role in the process, is partially overcome in this paper by representing the process in terms of force balance to which a few simplifying hypotheses are applied. The goal of this approach is to make the description entirely analytical thus avoiding any empiricisms that could limit the generality of the study. The model realised is able to provide reliable kinematic data, which prove to match significantly with data available in literature, especially for higher Reynolds numbers. The paper also shows an application of the model to the computation of the aerial evaporation of a water droplet: quantitatively, this part of the study is able to provide an upper limit of the friction-induced phenomenon only, however qualitatively the consequent analysis of the results opens a new window on the full understanding of the aerial evaporation of sprinkler water, highlighting the possible role played by certain environmental parameters, such as air friction and air temperature. This latter analysis also involved careful experimental activity, which is also presented herein
7° Congresso Nazionale AIGE
No full textIl 7° Congresso Nazionale dell'Associazione Italiana Gestione Energia si svolge nella Provincia di Cosenza, presso il Centro Congressi dell'Università della Calabria, nel Comune di Rende. La manifestazione si tiene in Calabria per la prima volta
Experimental study of water droplet boiling on hot, non-porous surfaces
No full textIn this paper, the results of a series of experimental tests on single- and multi-droplet boiling systems are presented and discussed. The main objectives of the present study are: a) to investigate experimentally the effect of the boiling onset on the evaporation rate of water droplets; b) to measure the evolution of the solid surface temperature during evaporation; c) to examine the possibility of improving spray cooling efficiencies. The behavior of small water droplets (from 10 to 50 mu l) gently deposited on hot, non-porous surfaces is observed. The evaporation of multi-droplet arrays (50 and 100 mu l) under the same conditions of the single-droplet tests is analyzed. In particular, the conditions which determine the onset of nucleate and film boiling are stressed out. In the experimental tests, the interaction of different materials with several multi-droplet systems is monitored by infrared thermography. The spray cooling efficiency is related to the solid temperature decrease as a function of the water mass flux. In the present study, the effect of varying the droplet volume and the mass flux is also analyzed and discussed. The results on the droplets evaporation time and on the solid surface transient temperature distribution are also compared with the data obtained by the same authors during the analysis of droplet evaporation in total absence of nucleate and film boiling. In order to analyze the different behavior of the evaporating droplet as a function of the solid surface thermal conductivity, evaporative transients on aluminum, stainless steel and macer (a glass-like, low-conductivity material) are considered
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
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