1,721,029 research outputs found
Preliminary design of a 75 m Mega Yacht with diesel - Electric hybrid propulsion powered with hydrogen FCs
No full textThe naval research and industry are facing with the significant challenge of ensuring carbon neutrality for the
future of sustainable transportation. This imperative arises from the fundamental role that this sector occupies in
global trade and the transportation of people.
To achieve this goal, the use of green propulsions and alternative fuels play a central role, guaranteeing a
significant reduction of ships global emissions and the respect of rules imposed in the Emission Control Areas
(ECAs), therefore the preservation of the sea. If environmental awareness has been a reality for which efforts
have been underway for years in land-based transportation, the same cannot be said for the maritime industry.
For this reason, and with the aim of introducing innovative and more eco-compatible solutions, the paper
presents the methodology used for the preliminary design of a 75-m Mega Yacht and sizing of the hybrid dieselelectric
propulsion system equipped with hydrogen powered fuel cells and pressurized storage. As current
technology does not support long-range sailing with full hydrogen propulsion, the hybrid propulsion was
preferred. The configuration presented offers the flexibility of full electric sailing for short distances (up to 130
nautical miles) or to access protected areas, while also allowing traditional propulsion when hydrogen refuelling
infrastructure is unavailable at ports or when faster sailing is required.
The power unit consists of four FCs with a total power of 540 kW, two 180 kW electric motors combined with
two 1765 kW thermal engines. The hydrogen storage area is composed of 105 cylinders with a total capacity of
21.3 m3 and a pressure of 350 bar, respecting the current regulations and guidelines for the use of hydrogen and
pressurized explosive gases onboard. Furthermore, the IMO criteria were met to verify the feasibility of the idea
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
Methanol and Fuel Cell for Cold Ironing Achieving Emission Reduction and Its Economic Assessment
No full textThe completely shipping sector is engaged toward the reduction of greenhouse gas emission. Both IMO and the EU already set their pathways along the GHG strategy aiming to reach a shipping sector fully carbon neutral. The two regulatory bodies issued a first set of requirements with further ones under preparation. High-Speed units will be indeed also involved by these efforts in a very specific way, considering their very peculiar operation profiles. In order to improve the carbon footprint for a high-speed craft, a reference unit (e.g. 50mt in length) is considered, engaging innovative technologies and new fuels. Being the port infrastructures also part of the sustainable mobility, the interaction between the ship and the harbor facilities are also considered. Ships at berth generate their electricity depending on their own auxiliary engines, emitting air pollutants and creating noise. This makes ports a major and growing source of pollution. Therefore, using fuel cell, main aims of this paper are the shore-side power concept economic analysis and the shore-side power and environmental effect
Ammonia as an Alternative Fuel on a Mega-Yacht: An Analysis of Case Studies Using Different Fuel Cell Technologies
No full textTo meet the aim of emission reduction and decarbonization, the study of alternatives to traditional fuels and thermal machines is increasing, in favour of new technologies, such as Fuel Cells (FCs) and batteries, and the use of innovative fuels, such as methanol, hydrogen and ammonia. In this study, the possibility of using ammonia as a hydrogen carrier for FCs has been investigated. In particular, both direct ammonia-fueled FCs (SOFC, AFC) and indirectly fueled FCs (PEMFC) have been considered. The case study of a 64 m length mega-yacht has been considered and the effects of the installation on board of these new technologies on the general arrangements have been evaluated. Different power configurations are proposed to allow both a hybrid and fully electric propulsion to reach zero-emission conditions. A fuel control strategy is also proposed to support the wide load variation
State of the art of high temperature fuel cells in maritime applications
No full textThe paper aims to make the state of the art on the applications of Fuel Cells (FCs) in maritime applications. It synthetically describes the Solid Oxide Fuel Cells and Molten Carbonate Fuel Cells technologies highlighting critical issues and advantages dealing with the maritime sectors. Several projects have been described in literature, the main focus are the assessments of potential for FC use, rules development, feasibility studies and concept design for testing FCs in various vessels. Low temperature FCs, in particular PEMFC fuelled by H2, are suitable for small and medium applications, high temperature FCs (HTFCs) for larger ones. The main conclusions are that no fundamental obstacles for the integration of FC-systems into commercial ships exist as well as no fundamental obstacles with respect to safety
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
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