1,721,019 research outputs found
A numerical analysis of an active magnetic refrigerant system with a multi-layer regenerator
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A dimensionless numerical analysis for the optimization of an AMR cycle
No full textRefrigeration by an active magnetic regenerative system (AMR) is potentially more attractive, as compared to conventional
techniques. Indeed, devices based upon an AMR cycle are more efficient, compact, environment-friendly and can operate
over a broad range of temperatures. In this paper, attention is focused to the near room-temperature range.
On the other hand, however, the AMR cycle poses a variety of complex problems, in terms of fluid dynamics, heat transfer
and magnetic field. In order to identify the optimal operational parameters, the design and optimization of a magnetic refrigeration
system can be supported by modelling. In this paper, a dimensionless approach was adopted to simulate an AMR cycle following
a Brayton regenerative cycle. In the simulation, the temperature range that has been explored is 260 – 280 K and 275 – 295 K.
The heat transfermediums are, respectively, water–glycol mixture (50% by weight) and pure water. The Gd0.8Dy0.2 alloy and pure
Gd have been chosen as constituent material for the regenerator of the AMR cycle. With this model, the influence of the different
parameters on cycle efficiency has been analysed. In particular, the study has been focused on the influence of the secondary fluid
properties,magnetic material particle diameter, fluid blow time, secondary fluidmass flow rate, regenerator geometry and effect of
axial thermal conduction. The model enables to find optimal dimensionless numbers in order to maximize the cycle
performances. The results can be extended to widely different situations and therefore can be easily employed for the design
and the optimization of new experimental prototypes
A comparison of different magnetic materials in an AMR cycle in the near room temperature range
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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
GeoThermag: a geothermal magnetic refrigerator
No full textMagnetic refrigeration has played an important role in the scientific landscape in recent years and could potentially be an alternative to vapour compression technology. Although new prototypes have recently been developed and new material refrigerants have been tested, there is still no equipment that can be used in the refrigeration industry. In the present work, we demonstrate how magnetic refrigeration can be applied to climate system environments by combining the technology of magnetic refrigeration with that of low temperature geothermal energy. Thus, we introduce the concept of GeoThermag. After describing the GeoThermag system in detail, we report experimental results that demonstrate the validity of this application. These experimental tests were obtained by using a magnetic refrigerator that was connected to a geothermal probe. Using 1.20 kg of gadolinium, we found that the GeoThermag system configured in this manner is capable of providing cold water to feed a radiating panel and to develop a cooling capacity of 190 W with a COP of 2.20
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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