1,720,970 research outputs found
Analysis and optimization of fuel cell cogeneration systems for application in single-family houses
No full textThe world’s demand of energy is projected to double by 2050 in accordance with population growth and with the industrialization of developing countries. The supply of fossil fuel could be limited and even worse is concentrated in a few regions of world, while demand is growing everywhere. One promising alternative to fossil fuel is hydrogen which is abundant and generously distributed through the world without regard for national boundaries. The aim of this paper is to explore this early market opportunity for fuel cell cogeneration systems in buildings and to determine the conditions under which they might compete with the alternative of purchased power. It is suitable to identify and to provide solutions for problems encountered in adapting these systems to buildings through a process which involve three steps:
- Determination of buildings energy annual demand compiled by a data acquisition system or logged daily by operators
- Characterization of a specific fuel cell in terms of amount of heat flow available and its temperature level, based on the power output of the system
- Calculation of annual energy costs (natural gas fuel and possibly purchased electrical energy) for providing power, heat and air conditioning and comparison with operating costs of existing buildings. The energy cost savings provided by the various cogeneration systems were used to provide estimates of what capital costs for each of these systems might be economically justified
A numerical model is developed to perform a fuel cell cogeneration system, coupled with a Thermal Energy Storage (TES), in accordance with energy requirements of a single-family residence. The objective of the mathematical model is to calculate the energy allocation for each system component and to determine fuel use of the system on hour basis. The operation of the cogeneration system is dependent on the temperature of TES (TTS ) which varies during the hours. If the tank is hot enough (TTS ≥ Thwx temperature limit for electric domestic water heating) it can supply the entire domestic water load, otherwise if the tank is too hot (TTS ≥ Tfcx temperature limit for external heat rejection from the fuel cell) the heat transfer from the fuel cell will be limited.
Two conventional systems connected to public grid are investigated as alternatives to the cogeneration ones
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
Functional and structural features of the oxyanion hole in a thermophilic esterase from Alicyclobacillus acidocaldarius.
No full textCrystal structure of an S-formylglutathione hydrolase from Pseudoalteromonas haloplanktis TAC125
No full textS-formylglutathione hydrolases (FGHs) constitute a family of ubiquitous enzymes which play a key role in formaldehyde detoxification both in prokaryotes and eukaryotes, catalyzing the hydrolysis of S-formylglutathione to formic acid and glutathione. While a large number of functional studies have been reported on these enzymes, few structural studies have so far been carried out. In this article we report on the functional and structural characterization of PhEst, a FGH isolated from the psychrophilic bacterium Pseudoalteromonas haloplanktis. According to our functional studies, this enzyme is able to efficiently hydrolyze several thioester substrates with very small acyl moieties. By contrast, the enzyme shows no activity toward substrates with bulky acyl groups. These data are in line with structural studies which highlight for this enzyme a very narrow acyl-binding pocket in a typical alpha/beta-hydrolase fold. PhEst represents the first cold-adapted FGH structurally characterized to date; comparison with its mesophilic counterparts of known three-dimensional structure allowed to obtain useful insights into molecular determinants responsible for the ability of this psychrophilic enzyme to work at low temperature
The Crystal Structure of an EST2 Mutant Unveils Structural Insights on the H Group of the Carboxylesterase/Lipase Family
No full textDispelling 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
- …
