1,721,001 research outputs found
Analyzing enterprise networks needs: Action research from the mechatronics sector
No full textNew business models and theories are developing nowadays towards collaborative environments direction, and many new tools in sustaining companies involved in these organizations are emerging. Among them, a plethora of methodologies to analyze their needs are already developed for single companies. Few academic works are available about Enterprise Networks (ENs) need analysis. This paper presents the learning from an action research (AR) in the mechatronics sector: AR has been used in order to experience the issue of evaluating network needs and therefore define, develop, and test a complete framework for network evaluation. Reflection on the story in the light of the experience and the theory is presented, as well as extrapolation to a broader context and articulation of usable knowledge. © 2009 IFIP
Micro-cogenerazione da biomassa con tecnologia di pirolisi
Full text linkIl lavoro sintetizza le attività di ricerca e sviluppo in corso presso l’Università di Perugia sull’impiego del processo di pirolisi per la conversione energetica di biomasse. Viene descritta la tecnologia IPRP (Integrated Pyrolysis Regenerated Plant), originalmente proposta dagli autori che prevede un pirolizzatore a tamburo rotante associato ad una microturbina a gas. Successivamente si descrive l’attività di modellazione numerica dell’impianto per ottimizzare i parametri di funzionamento in funzione della taglia, e viene illustrato il tamburo rotante da laboratorio progettato e realizzato interamente presso il Dipartimento di Ingegneria Industriale dell’Università di Perugia. Si descrive infine la progettazione e realizzazione di un impianto pilota IPRP da 80 kWel, completo di microturbina, cofinanziato dalla Regione Umbria, costruito ed attualmente in fase di collaudo presso la sede di Terni. Dai risultati della ricerca è stata costituita nel 2005 la società di spin-off accademico denominata BIO-NET-Biomasse e Nuove Tecnologie Srl per la commercializzazione della tecnologia IPRP
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
Analisi CFD di una camera di combustione per microturbina alimentata con gas naturale e con syngas da biomasse
No full textLe microturbine sono macchine di piccola taglia per la generazione elettrica distribuita, usualmente alimentate a gas naturale; tuttavia si può pensare di impiegare anche combustibili gassosi a basso potere calorifico, ottenuti mediante processi di pirolisi e/o gassificazione a partire da biomasse di varia origine.
L’alimentazione con gas di sintesi al posto del gas naturale può comportare l’insorgere di diverse problematiche, legate alle differenti caratteristiche dei combustibili: difficoltà di accensione, instabilità di combustione, incremento delle emissioni inquinanti, problematiche di sporcamento.
La simulazione termofluidodinamica numerica del processo di combustione interno alla camera rappresenta uno strumento di indagine potente, utilizzabile per identificare le problematiche dell’impiego di combustibili a basso potere calorifico entro le microturbine e per suggerire eventuali modifiche al progetto della camera o diverse modalità di gestione della combustione.
La presente memoria descrive uno studio condotto su di una specifica camera di combustione anulare di una microturbina commerciale. Si riportano i risultati numerici ottenuti con diversi codici CFD commerciali utilizzati per riprodurre la fluidodinamica interna e si mostra il confronto con alcuni dati sperimentali relativi alle emissioni allo scarico in condizioni di pieno carico e carico parziale, quando la microturbina è alimentata a gas naturale. Inoltre, si forniscono i risultati numerici ottenuti in presenza di combustione di un assegnato gas di pirolisi ed infine nel caso di co-combustione di gas naturale in miscela con il gas di sintesi. In particolare, in questo studio preliminare sono state utilizzate strategie di modellazione della termofluidodinamica basate sull’analisi di tipo RANS e considerando una cinetica chimica non dettagliata.
L’analisi condotta mostra che nel caso di alimentazione con gas di pirolisi la distribuzione di temperatura interna al combustore risulta fortemente alterata, con uno spostamento della zona di reazione primaria e con potenziali conseguenze in termini di emissioni allo scarico
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
Humid Air Turbine (HAT) cycle: state of the art and perspectives
No full textIn the last fifteen years several different energy conversion systems configurations were proposed to increase efficiency of power plants. In particular, those based on the increase of gas turbine performance seem to be the most interesting solutions for electrical power production in the next century. The highest efficiency values are actually achieved by the combined cycles that utilize the heat rejected from a gas turbine to generate steam which is then used in a steam turbine to produce additional power. This, however, complicates plant configuration and operation. Another solution to increase gas turbine performance, with a simpler system, is steam injection, which increases the flow rate in the turbine and reduces NOx emissions. Among these cycles, starting from the General Electric STIG (Steam Injection Gas Turbine, Brown and Cohn, 1981, Tuzson, 1992, Rice, 1993a-c) and the Cheng cycle (Saad and Cheng, 1992), the one that seems to provide the best performance in terms of power and efficiency is the Humid Air Turbine (HAT) cycle (Rao and Joiner, 1990). Since the first HAT cycle configuration was presented, some thermodynamic and economic analyses have been done on the cycle behavior. The optimization of the basic parameters of the HAT cycle (Bettagli et al., 1995, Chiesa, et al., 1994, Stecco, et al., 1993a-b, Xiao, et al., 1994, Rosén, et al., 1994, Hansen and Nielsen, 1996, Klara, et al., 1996, Lindgren, et al., 1992), the study of the effect of an external heat exchanger for the refrigerators circulating water (Stecco, et al, 1993a-b), the analysis of heat and water recovery from the exhaust gasses (Bettagli and Facchini, 1994; Bidini et al., 1996; Desideri and Di Maria, 1996; Bombarda, 1995, De Paepe and Dick, 1997, Qun, et al., 1997, Xueyou, et al., 1996), yan, et al. 1996), the effect of blade cooling bleeding point (Gallo et al., 1996), are some of the principal contributions to the knowledge of the HAT cycle. An important contribution has also been given by Nakhamkin, et al. (1995, 1997) with the introduction of the CHAT (Cascaded Humidified Air Turbine). This paper reviews some of the most significant results presented in the above papers, obtained by the research groups at the Universities of Perugia and Florence in Italy and the University of Campinas in Brasil. An economic analysis has been added to understand the influence of the main economic parameters on the cost of generated electricity. This is important when the cycle is studied in different economic scenarios such as the Europe and Latin America
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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