1,721,436 research outputs found
Holistic approach to design a fuel cell hybrid system for maritime application
No full textThis thesis presents the holistic design of a hybrid power system and propulsion system
for ferry applications based on a Proton Exchange Membrane Fuel Cell (PEMFC). In
the zero carbon energy transition scenario, hydrogen fuel cell (FC) technology is the
protagonist for stationary power systems and medium to long range electric transport.
In marine applications, especially for vessels operating in coastal areas, PEMFCs are
a solid alternative to batteries, as they can provide a higher energy density due to
the separation between the PEMFC and the energy storage (H2 tank). At present,
the penetration of this technology into marine power systems is limited by the cost of
manufacturing fuel cells and the high purity of hydrogen as a fuel. In addition, companies
offering PEMFC-based power generation solutions to the marine market must design the
product to meet customer requirements, which are different for each application. This
significantly increases the cost and resources involved in each project.
The aim of this work is to provide an effective tool for the preliminary design of
PEMFC systems that considers the fuel cell in a hybrid configuration, taking into account
the interaction with all other equipment on board. The holistic approach, together with
the sizing of the FC system, provides important insights into the sizing of the other
power system components.
The simulation framework, developed in the Matlab-Simulink environment, uses
models of different complexity for each power system component, taking into account
the degree of interaction with the PEMFC. Thus, the other energy sources, such as batteries
and internal combustion engines, are modelled taking into account the dynamics
of these systems and the efficiency of the converters used to distribute the energy to
the electrical grid. The proposed on-line energy management system (EMS) selects the
operating mode, taking into account the ship’s power requirements and the remaining
battery capacity, and chooses how to use the power available on shore.
The modelling included not only the power systems but also all the ship’s characteristics,
from hull resistance to propeller power. This was done in the case of a new ship
design to know the power required during operation.
The simulations assess the feasibility of the hybrid PEMFC power system, taking
into account the main criticalities reported in the scientific literature, such as transient
performance, FC degradation and thermal management. The optimisation framework then finds the solution to achieve the best performance in terms of FC stack degradation
over one year of ship operation.
The chosen case study is an existing ferry that is currently powered mainly by batteries
and diesel generators in an DC network. The proposed results of the zero-emission
power system configuration, based on the PEMFC and the battery, show the performance
of the whole system during 5100 operating hours, and in particular, the efficiency
of the PEMFC and of the applied thermal management strategy
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
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
Inorg.Chem., 24, 3828-3831 (1985). "Equilibria and Mechanism of the Interactions of Indium(III) with the Indicator PAN"
No full text
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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