1,720,957 research outputs found
LIBS Collection Optics : comparative analysis of different mirror-based configuration
Get PDFWe have evaluated the efficiency of different reflection based optical systems using numerical simulation. We have realized and started testing the most promising one
Effect of the temporal integration on the accuracy of the measured concentration in LIBS measurements
Get PDFWe have developed a simulation program that allows to calculate the plasma emission spectrum of a coal sample in a LIBS experiment. We used the acquired data to evaluate the effect of temporal integration on the accuracy of measured concentration obtained using the calibration free method
DEVELOPMENT OF AN INNOVATIVE LIBS SYSTEM FOR ON-LINE QUANTITATIVE ANALYSIS OF RAW COAL.
Get PDFEvery day in the world 64’125 GWh of electricity are produced and consumed: to satisfy this huge demand, many different power sources are employed, and in the last years the renewable energies share has kept on increasing. However, coal is still the main energy source and, thanks to the huge growth of China energy production, the amount of electrical energy produced this way is increasing: every day 12.1 million tons of coal are burned to fulfill 40% of the global electrical energy demand. In Italy, even if only 16.7% of the total power generation is obtained with coal combustion, coal is still the third power source, after natural gas and hydroelectric, and we have to import it in the amount of 17.5 million tons every year.
Coal has an extremely variable composition, and heat power, pollutants generation and, consequently, cost, strongly depends on that composition; for these reasons whoever deals in coal is always on the look for instruments that allow to perform faster and more accurate analysis of coal composition.
Devices able to perform on-line quantitative analysis of coal chemical composition are already commercially available; however, they are extremely expensive and must undergo strict regulations, due to the fact they employ either x-rays, gamma rays or neutrons. On the other hand, laser induced breakdown spectroscopy, or LIBS, has proven itself as a cost effective solution and has found many applications in other fields.
In my Ph.D. thesis I have developed a working prototype for on-line quantitative analysis of coal based on LIBS, following every step of its realization. The main task has been the design and realization of an innovative collection optic that allows to perform measures on raw coal, at a distance of 1 meter from a conveyor belt; the innovative part consists in the fact that it doesn’t resort to the use of moving parts, decreasing its cost and increasing its reliability. My tasks also included the development of the software for data collection and analysis, the test of the instrument and its calibration . I have been deeply involved also into the choice of the components and the design of an instrument for the test in a real power plant
Validazione della tecnica LIBS per l’analisi della composizione di carbone in pezzi edefinizione dei requisiti di un prototipo per misure su impianto
No full textIl documento descrive l’attività relativa allo sviluppo di un sistema LIBS (Laser Induced
Breakdown Spectroscopy) da utilizzare per l’analisi in linea della composizione chimica del
carbone in ingresso ai mulini di macinazione nelle centrali termoelettriche alimentate a
carbone
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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