1,721,014 research outputs found
Reducing the environmental impact of large cruise ships by the adoption of complex cogenerative/trigenerative energy systems
Full text linkThe International Maritime Organization (IMO) has developed new and stricter rules about environmental
impact of big vessels. Those rules are going to widen significantly the so called Emission Controlled Areas (ECA)
and to generally gain more control over pollution levels over the seas.
The solution that most ship-owners are going to prefer is most likely to be the implementation of pollutant
emissions reducing systems, such as Scrubbers and Selective Catalytic Reactor Systems, to dampen emissions
produced by the present propulsion systems, based on Internal Combustion Engine (ICE) which burns the cheap
but polluting Heavy Fuel Oil (HFO).
An alternative solution, based on the adoption of Gas Turbines (GT) in the propulsion system, fuelled by
Marine Gas Oil (MGO), can be taken into account, allowing considerable savings in weight and space occupied
and lover NOx as well as SOx emissions than those of ICEs, even if with a loss in the engine efficiency (Armellini
et al., 2018).
In this paper, the possibility of using simultaneously ICEs and GTs as well as the use of trigeneration system is
analyzed, with the aim of exploiting the positive feature of both the engine systems. The paper provides a
quantitative comparison among different hybrid engines configurations (ICEs and GTs working together) making
reference to a large cruise ship as a real case. Considering a cruise ship rather than a cargo ship implies an
important and time-dependent thermal energy demand, so that an onboard trigeneration system may result a
convenient solution
Gas turbine blades internal cooling: Design, development and validation of a new rig for heat transfer measurements under rotation
No full textThe contribution describes part of the work carried out on a wider research project aimed to set up a new tool to study rotational effects on the heat transfer distribution inside realistic cooling passages for gas turbine blades.
Transient thermochromic liquid crystals (TLC) measurement technique is chosen in order to obtain spatially resolved heat transfer data. This obliges to perform the transient measurements with a cold temperature step on the coolant flow, in order to replicate correctly the buoyancy effects induced by rotation. This target is achieved by a new facility which components and working principle have been the subject of previous contributions. In the present paper, the progresses made in the development of the data processing methodology are described at first. Successively, a first step into the demanding rig and methodology validation process is commented by exploiting the results of a wide test campaign on a simple cooling channel geometry
Experimental Investigation of the Effects of Blowing Conditions and Mach number on the Unsteady Behavior of Coolant Ejection through a Trailing Edge Cutback
No full textThe management of newborns with esophageal atresia and right aortic arch: A systematic review or still unsolved problem
No full textAim of the study: The management of newborns with esophageal atresia (EA) and right aortic arch (RAA) is still an unsolved problem. This study provides a systematic review of epidemiology, diagnosis, management and short-term results of children with EA and RAA.Materials and methods: The PubMed database was searched for original studies on children with EA and RAA. In each study, data were extracted for the following outcomes: number of patients, associated anomalies, type of surgical repair, morbidity and mortality rate.Results: Eight studies were selected, including 54 patients with EA and RAA. RAA was encountered in 3.6% of infants. Preoperative detection of RAA was reported in 7 of them. In these patients, primary anastomosis was achieved through the right approach in 3 (thoracotomy in 2 and thoracoscopy in 1) while the left approach was the primary choice in 4 (thoracotomy in 2 and thoracoscopy in 2). No significant differences were found between the right and left approaches with regard to leaks (P=0.89), strictures (P=1) ormortality (P=1). In 47/54 patients (87%) RAA was noted during right thoracotomy, and primary anastomosis was achieved through the same approach in 29 (61.7%); conversion to other approaches (left thoracotomy or esophageal substitution) was performed in 15 children (38.3%). No significant differences were found between primary left thoracotomy (LT) and LT after RT with regard to leaks (P=0.89), strictures (P=1) or mortality (P=1).Conclusions: Skills and preferences of the surgeon still guide the choice of surgical approach even when preoperatively faced with RAA. A multicenter, prospective randomized study is strongly required. (C) 2016 Elsevier Inc. All rights reserved
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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