1,721,299 research outputs found
A new shape dependent drag correlation formula for non-spherical rough particles. Experiments and results
No full textThe drag of non-spherical rough particles has been investigated in a wide range of Reynolds numbers (0.03-10,000). The study is based on experimental measurements of the terminal velocities of irregular particles falling in fluids of different densities and viscosities. The particle shape is described by a shape factor that takes into account both sphericity and circularity, which are measured via image particle analysis techniques. This shape factor is particularly suitable for non-spherical and highly irregular particles. The drag coefficient has been correlated to the particle Reynolds number and the shape factor and a new correlation law has been found; the correlation has the functional form of a power law. Due to the mutual dependency of the particle terminal velocity on the drag coefficient, which in turn depends on the particle shape and Reynolds number, an iterative procedure needs to be designed for calculating the terminal velocity of particles of a specific size and shape. Such a procedure is adopted herein and a spreadsheet and a Fortran 90 code allowing the iterative calculation are provided in the Supplementary Material. The fitting of experimental measurements with our model calculations show that our new law predicts the drag coefficients and the terminal velocity of irregularly shaped particles, as volcanic ash, more accurately than other shape-dependent drag laws
Role of echocardiography for the assessment of left ventricular dysfunction due to cancer treatments
No full textThe use of echocardiography for the assessment of patients undergoing potentially cardiotoxic cancer treatments and for follow-up of treated patients is increasing and has become a significant public health problem due to the need for repeated examinations over time. Despite the technological advances of echocardiography, there are still uncertainties about how best to use this technique to identify and guide the management of cardiotoxicity. The purpose of this article is to discuss the role of echocardiography in the study of ventricular dysfunction due to cancer treatments, with the aim to clarify the main echocardiographic information to be provided, the methods to apply and the strategies to implement to streamline as much as possible the use of echocardiography in the field of cardioncology
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
Integration of a new shape-dependent particle-fluid drag coefficient law in the multiphase Eulerian-Lagrangian code MFIX-DEM
No full textA new shape-dependent fluid-particle drag law has been added into the open source fluid dynamic software MFIX-DEM (MFIX-Discrete Element Method), which is the Eulerian-Lagrangian version of the classic MFIX Eulerian-Eulerian multiphase flow model. The drag law had been obtained by previous settling experiments of volcanic pumices in a motionless Newtonian liquid (water or alcohol). Pumices are characterized by a highly irregular shape, which is much different from a sphere and drastically influences fluid drag. The new drag law defines the particle-fluid drag coefficient as a function of both the fluid regime and particle characteristics, of which the shape factor is a compact descriptor that quantifies how the particle shape differs from a simple sphere. As a validation of the integration of the new drag law in the simulation software MFIX-DEM, the code has been used to replicate the experiment results. The comparison with simulations performed with other formulas demonstrates that, by means of the new drag law, a significant improvement in the capability of the MFIX-DEM code to predict the terminal velocities of irregularly shaped particles is obtained. Thanks to this implementation, MFIX-DEM should be used, from now on, for simulating fluid-particle flows in which the particles are significantly different from simple spheres, as is usually the case of environmental flows like explosive eruptions or ash and pollutant dispersal. Based on the results of this research, in the future an improved version of MFIX-DEM will be also presented, with a drag law useful also in the case of mixtures to be treated with a Eulerian-Eulerian multiphase model. (C) 2014 Elsevier B.V. All rights reserved
Experimental campaign and numerical analyses of thermal storage concrete modules
No full textA three-stage study on the behaviour of storage plants employing concrete with upgraded thermo-mechanical characteristics is here developed. The first stage defines the experimental campaign on a mixing at improved conductivity, via the SolTeCa experimental system, with review of the storage elements geometry, location of thermocouples and cycling procedures. The experimental results, obtained by ENEA via a comparison with appropriately performed numerical calculations, are interpreted during the second stage. Finally, a first design of a new equipment for the thermal cycling of storage elements up to 400 °C is proposed, based on Joule-effect heating. The numerical results are reported, in order to understand the thermal dynamics as well as the induced thermo-mechanical effects on concrete elements. © 2017 Elsevier Lt
Evaluation of left ventricular systolic function during atrial fibrillation: Is it reliable?
No full textFor adequate treatment of patients with atrial fibrillation (AF) clinicians need information on left ventricular (LV) systolic function. This is generally evaluated using echocardiography to calculate LV ejection fraction (LV-EF) or global longitudinal strain (GLS), which can detect early systolic abnormalities when LV-EF is still normal. In using both LV-EF and GLS the key point is that measures should be reliable and reproducible, regardless of cardiac rhythm. Unfortunately, many clinicians question the reliability of the echocardiographic measures during AF because of several reasons. First, AF patients are often excluded in echocardiographic studies, thus data for the validity of systolic function indices during AF are limited [ 1 ]. Second, the prognostic value of cardiac function parameters may be affected by AF [ 2 ]. Third, methods to improve assessment of LV function during AF are rarely applied in echocardiographic practice because they are generally cumbersome and time-consuming, and many echocardiographers just rely on eye-ball evaluations. Thus, assessment of cardiac function in patients with AF is problematic
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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