1,720,979 research outputs found
Design optimization of the phase change material integrated solar receiver: A numerical parametric study
No full textDish-Micro Gas Turbine (D-MGT) systems can be an effective way of power production (<100 kW) in rural areas having limited access to electricity. In such no fuel assisted systems, the stability of the input thermal power to the MGT is an important concern as MGT is sensitive to the temperature variations caused by the natural fluctuation of the solar flux. To reduce this effect, a novel solar receiver has been proposed integrated with a Phase Change Material (PCM) for the short-term thermal energy storage. The proposed receiver is cylindrical shaped filled with PCM, with a conical cavity on the front surface and heat transfer fluid tubes immersed in the PCM. This paper deals with the investigation of the optimum design point of the proposed receiver based on the required input parameters of the MGT. The numerical simulations have been conducted using Computational Fluid Dynamic methods to pre-evaluate the effect of many controlling parameters on the temperature, PCM liquid fraction, pressure loss and outlet thermal power of the receiver. Surface-to-Surface (S2S) radiation model has been employed along with the ray-tracing model for the constant concentrated solar flux of 500 kW/m2 on the receiver aperture surface. The influencing factors considered in this study include the high-temperature PCMs, receiver cavity dimensions, incident solar flux, hot wall thickness, tube diameter and the number of the tubes, pressure drop inside the tubes and the inlet mass flow rate. Results demonstrate the considerable effect of each variable on the receiver output parameters, and this leads to the identification of optimum design point. The result of the study offers valuable guidelines for the receiver development for further experimentation
Design of high-temperature solar receiver integrated with short-term thermal storage for Dish-Micro Gas Turbine systems
No full textSmall-scale concentrated solar power plants equipped with Micro Gas Turbines (MGTs) could be an effective way for power production in the off-grid areas. One of the most relevant concerns for such no fuel-assisted systems is the solar radiation fluctuations, which reduce system performance and, in the worst cases, can damage the MGT. To overcome this issue, the solar receiver should have sufficient thermal inertia averaging the thermal power inputted in the MGT. In the present study, the design of a novel high-temperature cavity solar receiver is presented for the application in the Dish-MGT system. The receiver has been integrated with a PCM for the short-term thermal energy storage (15–30 min). The design process was based on the main parameters of the solar dish and MGT. The thermal model enables the variation of different geometrical factors and input parameters to identify the optimum receiver design. Moreover, it can be used for the evaluation of heat losses from the cavity surface and temperature distributions in the PCM. A 1D steady-state model has been developed for the heat loss calculation from the cavity and corresponding cavity surface temperature, as well as for the evaluation of number and dimensions of the MGT working fluid tubes. Furthermore, the PCM melting and the transient temperature distribution inside the PCM domain have been determined analytically with the help of a 1D thermal model. The initial design results showed that solar receiver integrated with the high-temperature PCM is a promising option for the stable outlet temperature for MGT
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
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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