1,720,971 research outputs found
Tecniche innovative per la rivelazione e la separazione di segnali sovrapposti nel canale del radar secondario di sorveglianza
Full text linkIn questo lavoro è stato affrontato il problema della corretta ricezione di segnali a 1090 MHz in ambienti ad alta densità di traffico. I segnali oggetto degli studi sono quelli utilizzati dai sistemi per la sorveglianza del traffico aereo (ATC): il radar secondario di sorveglianza (SSR), il sistema ADS-B (Automatic Dependent Surveillance-Broadcast), i sistemi di multilaterazione (MLAT e WAM), il sistema TIS-B ed il sistema T-CAS (Traffic Collisions Avoidance System). Le sorgenti dei segnali sono: i transponder avionici, i transponder veicolari e le stazioni trasmittenti del sistema TIS-B (Traffic Information System – Broadcast). I transponder trasmettono segnali di modo convenzionale e di modo S a seguito di interrogazioni da parte del radar secondario di sorveglianza, da parte di sistemi MLAT/WAM attivi e da parte dei sistemi T-CAS. I transponder di modo S inoltre trasmettono anche dei segnali spontanei detti squitter. Le stazioni TIS-B trasmettono segnali di modo S con la funzione di aggiornare gli aeromobili dotati di ADS-B sul traffico di aeromobili non dotati di ADS-B. Un ricevitore a 1090 MHz collocato in un ambiente ad alta densità di traffico possiede una probabilità non trascurabile di ricevere segnali sovrapposti nel tempo, soprattutto se dotato di antenna ricevente omnidirezionale. Inevitabilmente una tale situazione impedisce la corretta ricezione e decodifica di tutti i segnali, pregiudicando l’integrità della sorveglianza. Le tecniche proposte per affrontare il problema della ricezione di segnali sovrapposti sfruttano la diversità di antenna per rivelare la presenza di segnali sovrapposti e separarli. Tali metodi prevedono l’uso di una antenna ad array ed un ricevitore multicanale. Viene proposta anche una soluzione basata sull’uso di un ricevitore mono canale ed antenna omnidirezionale. Gli algoritmi presentati sono stati valutati tramite dei test utilizzando segnali reali registrati. Infine viene mostrato come aumenta la capacità del canale a 1090 MHz grazie all’utilizzo delle tecniche proposte.This work addresses the reception problem of 1090 MHz signals in high traffic density environment. The 1090 MHz signals are used in air traffic control systems: The secondary surveillance radar (SSR), the ADS-B (Automatic Dependent Surveillance-Broadcast), the multilateration systems (MLAT and WAM ), the TIS-B (Traffic Information System - Broadcast) system and the T-CAS (Traffic Collisions Avoidance System). The signals sources are: the avionic transponder, the vehicular transponder and the TIS-B ground stations. The transponders transmit conventional and Mode S signals after receiving an interrogation by the secondary radar surveillance systems, by active MLAT / WAM and by T-CAS systems. Mode S transponders also transmit squitters, i.e. spontaneously emitted signals. The TIS-B ground-stations transmit Mode S signals in order to update the non-ADS-B traffic to the aircraft equipped with ADS-B (it is an ADS-B gap filler). A 1090 MHz receiver placed in a high traffic environment has a significant probability of receiving signals overlapping in time, particularly while using omnidirectional receiving antenna. Inevitably, this situation prevents the proper reception and decoding of all signals, compromising the integrity of surveillance. The thesis propose several methods to address the problem of overlapping received signal exploiting the antenna diversity, via an antenna array, for signals detection, separation, and decoding. These methods necessitate the use of an antenna array and a multichannel receiver, but also a mono-channel algorithm is proposed, which is useful for older systems that have only a single omnidirectional antenna. The presented algorithms have been assessed using real recorded signals. Finally the 1090 MHz channel capacity enhancement using the proposed methods is demonstrated
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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