1,720,957 research outputs found
An experimental and a numerical analysis of the dynamic behavior of PCM-27 included inside a vertical enclosure: Application in space heating purposes
No full textThe paper deals with the study of the heat transfer phenomena within a vertical enclosure containing PCM integrated inside a test cell with the dimension of (0.5, 0.5, 0.5 m3). An experimental framework was conceived and installed in the Thermal Processes Laboratory in Borj Cedria, Tunisia. The experimental investigation was carried out by measuring the temperature and the heat fluxes exchanged throughout the PCM vertical enclosure. It was found that during the heating phase the temperature inside the test cell equipped with the PCM vertical enclosure is about 28 °C. It was also found that once the PCM vertical enclosure is omitted the cell temperature inside the test cell ranges between 29 and 40 °C. A complete model was also formulated by taking into account various modes of heat transfer inside the PCM vertical enclosure. The numerical model was performed by following the temperature changes at the bottom position and at the high position of the PCM vertical enclosure. The numerical model followed also the evolution of the melting front during the melting process. The model was then exploited for the evaluation of the melting front evolution during the charging and the discharging processes. Another TRNSYS simulation was achieved to evaluate the feasibility of integrating the PCM vertical enclosure in a real building envelop. The results of the TRNSYS simulation showed that the integration of a well dimensioned PCM vertical enclosure enhances the thermal comfort of the occupant by reducing the thermal fluctuation and by improving the thermal inertia of the walls
Energetic, exergetic and economic analysis of an innovative Solar CombiSystem (SCS) producing thermal and electric energies: Application in residential and tertiary households
No full textThe endeavor of this paper is to study of the potential offered by the expenditure of an innovative Solar CombiSystem, SCS, used for the space heating load, the domestic hot water supply and the electric energy production. The investigation achieved in this work was based on an experimental and a simulation studies. A TRNSYS simulation program was achieved in order to evaluate the SCS monthly/annual thermal and electric performances. It was found that the proposed SCS covered between 20 and 45% of the SH energy needs by considering only solar energy. The result shows also that the SCS provided from 40 to 70% of the total DHW needs. It was also found that the SCS electric production ranged between 32 and 225 MJ/m2with a gain factor varying between 49 and 125%. An economic appraisal was also achieved to appraise the SCS feasibility. The results of the economic analysis show that the annual energy saved (ARE) and the payback period (Pb) based on electric water heater were respectively equal to 7618.3 kW h/year and 10.2 years. It was found that ARE and Pb based on gas/gas town were about 5825 m3and 8.7 years, respectively. The results of the economic analysis shows that the adoption of the SCS saves about 48% of electric energy and about 46% of gas/gas town kept back by the conventional system
Performance study of a solar combisystem for Tunisian houses with TRNSYS simulation
No full textThe endeavor of this work is the study of the energy performance of solar combisystem for Tunisian houses based on simulations using TRNSYS 16 software during the winter period when heating is needed. The mainly components of the system are: 12 m2 of flat-plate solar collector area, 750 l of hot water tank capacity, and an active layer integrated inside the 140
m2 of floor heating area. The studies of the thermal performances of the solar combisystem were achieved by comparing of two configurations: In the first configuration, the floor of the entire house is heated with a single active layer that passing through living room, washroom, bathroom, kitchen, dining room, bedroom and kids’ room. In the second configuration, the floor of the house is heated with two independent coils, the first through living room, washroom, bathroom and kitchen and the second through dining room, bedroom and kids room. The results shows that the optimal architecture of the solar combisystem consists on using of two active layers integrated inside the floor heating. The TRNSYS results show that the air temperature of others room ranges between 18°C and 26°C and the average solar fraction of the solar combisystem is 72%
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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