1,720,971 research outputs found
Analysis Techniques for Photovoltaic Modules Based on Amorphous Solar Cells
No full textThis paper focuses on the description of the analysis techniques of the PV module based on amorphous solar cells under indoor aging tests according to IEC 61646. The goal of this work is the knowledge about the dynamic characteristics of the PV module. The effect of indoor aging on the PV module performances will be also described. For this purpose, a simple technique, based on the analysis of the behavior of PV module biased by an AC signal on dark conditions, has been described and experimented. This technique allows evaluating easily and quickly some parameters such as the series, the parallel resistances and the capacitance affecting the dynamic AC model of the PV module. © 2016, King Fahd University of Petroleum & Minerals
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
A comparison between two different techniques to estimate the uncertainty of the low irradiance test
No full textThe purpose of the test 'Performance at low irradiance' is to determine how the electrical performance of the module varies with load at 25°C and at irradiance of 200Wm-2, using natural sunlight or a simulator class BBB or better conforming to the requirements of IEC 60904-9, instead of 1000 Wm-2 standard conditions. A device to change the irradiance to 200Wm-2 is required; its implementation shan't affect the relative spectral irradiance distribution and the spatial uniformity in accordance with IEC 60904-10. To this purpose the IEC 60904-10 recommends the use of mesh filters or neutral density filters. Mesh filters are believed to be the best method for large surfaces. It would be important to compare results and uncertainties related to the different solutions and discuss about pros and cons. This paper matches the results of two laboratories that adopt two different approaches. The low irradiance performance test has gained importance due to the always extensive use of PV as integration elements on buildings. © 2014 IEEE
Set of protocols for overall testing for CPV
No full textThe success of a new CPV prototype depends on modules quality and assembly compliance with existing Standards, such as IEC 62108, 62670, 62787, and others still under development/approval for performance evaluation. The overall CPV system reliability is based on the quality of the subcomponents such as the optics, the cells, the electronics and the assembly of the whole system, but there is a dramatic lack of technical specifications for new prototypes to comply with. The Italian project SCOOP (SOLAR CONCENTRATION TECHNOLOGIES FOR PHOTOVOLTAIC SYSTEMS) was aimed at developing an Italian network of laboratories and industrial facilities to enter the CPV market. The project, funded by the Ministry of Industry, started in 2009 and ended at the end of 2013. SCOOP addressed the development of solar cells, optical systems and inverters, to be used in four different CPV prototypes. The development of a network of laboratories specialized to test, verify and check components such as plastic materials, optics, cells, electronics and module/assembly at prototype and industrial scale has been one of the main targets of the project. Within the project a set of protocols for the testing of subcomponents, components, modules and the final systems have been defined and validated. © 2014 IEEE
New PV encapsulants: assessment of change in optical and thermal properties and chemical degradation after UV aging
No full textThis work aims to investigate the change in chemical and physical properties of different polymeric materials, potentially usable for photovoltaic modules encapsulation, caused by UV aging. Three classes of polymeric materials have been examined: ethylene-vinyl-acetate (EVA), thermoplastic polyolefins (TPO) and polyolefin elastomers (POE). EVA is currently the most used encapsulant in the photovoltaic field; TPO and POE are new materials, alternative to EVA, which can allow to overcome some of the reliability problems of photovoltaic modules linked to the degradation of EVA properties. Of each of these three material classes, different commercially available encapsulating polymer films, with different chemical formulations, have been examined. Stressful environmental conditions have been simulated in a climatic chamber and the associated changes in optical, thermal and chemical properties of the different encapsulants have been analysed and compared before and after UV aging. The link between the chemical structure, formulation and degradation of the encapsulants with their lifetime under simulated conditions of UV stress has been investigated by the assessment of the changes in thermal stability, optical transmittance, crystallinity, yellowness index and chemical degradation. This study helps to better understand the causes of the module performance reduction due to the degradation of the encapsulant material and is a guide for the selection of encapsulant films with improved characteristics, for the manufacture of more durable PV modules
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
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