1,721,074 research outputs found
A Simulation Model of Audio-Frequency Track Circuits
No full textThe new high speed railway lines, under construction in Italy, are electrified in 2x25 kHz – 50 Hz and adopt a signalling system with audio frequency track circuits (ranging from 2.1 kHz to 16.5 kHz). Although the choice of audio range is due to the necessity of avoiding interference problems between traction and signalling system, traction current presents a harmonic spectrum, due to the control systems, that can be cause of disturbances to track circuits operation with a possible impact on transportation regularity. With the aim of system availability assessment it becomes very important to develop reliable and robust models of the traction and signalling system. The paper illustrates a model adopted to simulate the audio frequency track circuits and implemented in Alternative Transient Program (ATP). The main results obtained are presented with the model validation, realized through a measurement campaign performed on the new railway line Rome-Naples, and with a sensitivity analysis of the same model
Measurement of the static magnetic field generated by large inductors for railway applications
No full textThis paper reports an experimental procedure for the characterization of the static magnetic field generated by large inductors installed in 50 Hz resonant filters, which are used for the reduction of electromagnetic interference induced in the Italian 3 kV dc railway infrastructure by nearby 25 kHz -50 Hz high-speed railway lines. The procedure and the related measurement system represent an effective tool to characterize dc magnetic-field levels in the railway environment in order to assess compliance with ICNIRP guidelines on human exposure to static magnetic fields
Fast and accurate measurement of radiated emission of moving trains according to IEC 62236
No full textThis work deals with the experimental characterization of the spectrum of electromagnetic radiated emissions (RE) of moving trains. In particular, a fully-automated measurement system and an optimized measurement procedure are designed and implemented, conforming to requirements of the
current International Standards IEC 62236-2 and EN 50121-2. The proposed system represents an optimization of a previous version, obtained by resorting to a unique hybrid biconical/log-periodic antenna instead of the two separate antennas (biconical and log-periodic), as suggested in the
aforementioned Standards. As a result, the measurement system is simpler, cheaper, it allows minimization of the number of required train runs (i.e. testing time and thus costs) and, as a whole, it leads to improved performance of the measurement process. Full compliance of the proposed
measurement procedure and system with IEC 62236 and CISPR 16 in terms of measurement uncertainty is discussed. As a specific example, test results obtained with measurements carried out along the high-speed railway line interconnecting Milan to Bologna, Italy, are reported
«I PIÚ LEALI E FEDELI SUDDITI DI SUA MAESTÀ» LA PRATICA DELLO SCRUTINIO NELLA RESTAURAZIONE BORBONICA (1815-1822)
No full textLa pratica dello scrutinio, ereditata dall’Ancien Régime e riadattata nel corso della prima metà dell’Ottocento, fu ampiamente utilizzata per valutare i percorsi professionali e politici dei pubblici ufficiali meridionali. Una sua prima applicazione avvenne all’indomani della Seconda restaurazione per attuare la ‘politica dell’amalgama’, attraverso la riorganizzazione degli organici ereditati dal Decennio francese e l’inserimento di nuove reclute. Seguirono numerose indagini effettuate dalle autorità locali di polizia nel più ampio contesto dei conflitti verificatisi nelle province durante l’intero Quinquennio borbonico. La frattura rivoluzionaria del 1820 portò a teorizzare un nuovo riordino e, con esso, un immancabile nuovo scrutinio delle condotte politiche e professionali del personale, rimasto poi incompiuto. Il ritorno dei Borboni a Napoli, al seguito del corpo di spedizione austriaco promosso dal congresso di Lubiana, portò alla formazione delle Giunte di Scrutinio al cui giudizio furono nuovamente sottoposti i pubblici ufficiali di ogni ordine e grado.
Il corpus documentario così formatosi nei fondi dei dicasteri di Grazia e Giustizia, della Polizia Generale e dell’Archivio Borbone, oggi conservati presso l’Archivio di Stato di Napoli, permette dunque di ricostruire le vicende di un gran numero di funzionari, specie nei ranghi del sistema giudiziario.
La ricerca si è concentrata sullo studio della pratica dello scrutinio come processo di identificazione politica degli individui. Da un lato si trattava infatti di una procedura di mappatura e di accountability degli apparati statali, volta a garantire fedeltà politica e affidabilità amministrativa in quanto aspetti inscindibili nella mentalità dell’epoca. Dall’altro, attraverso la raccolta di informazioni operata nei territori, lo scrutinio era uno spazio politico di negoziazione e ridefinizione delle identità socioprofessionali e politico-culturali, strutturalmente aperto tanto alla partecipazione e al dialogo con i poteri locali, quanto alla messa in moto di numerose agencies. In tal senso, lo scrutinio, in quanto prassi strutturante dello spazio politico meridionale, costituisce un osservatorio privilegiato sull’intreccio complesso di rappresentazioni simboliche tipizzate di carattere opposto all’interno del gruppo dirigente e dei notabilati locali, quali il ‘suddito fedele’ o il ‘traditore’.
Tracciandone le dinamiche e analizzandone le narrazioni contrapposte, lo studio si propone di ricostruire la vasta platea di attori coinvolti e le modalità con cui, volta per volta, si accreditarono «i più leali e fedeli sudditi» coinvolti nello spazio politico dello scrutinio. Rapporti riservati, relazioni sullo spirito pubblico, indagini, delazioni, testimonianze, petizioni, encomi: all’interno delle procedure di scrutinio è possibile ritrovare un’incredibile polifonia di voci sul rapporto tra intendenti, magistrati, commissari, vescovi, membri dell’amministrazione, del gruppo dirigente e dei notabilati locali. Pratiche testuali che ci raccontano molto anche su come, ben al di là della dimensione repressiva, lo scrutinio fu una pratica utilizzata per strutturare paradigmi di governo del reale, tracciando il profilo del pubblico ufficiale e riconfigurandolo nelle tumultuose contingenze politiche. La presente ricerca, fra i tanti temi sviluppati, ha cercato di collocare tale sperimentazione nel faticoso percorso collettivo di risposta alla crisi che aveva travolto il concetto di fedeltà nel Meridione della Restaurazione
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
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