1,720,958 research outputs found
Error-control codes and coded modulations for the optical fiber communication
No full textLes câbles de communication optique transcontinentale constituent un maillon essentiel dans les communications modernes. Ils permettent de faire transiter des volumes importants de données à grande distance, tout en induisant une faible latence de transmission. L'amélioration de leurs performances est un enjeu pour la société d'aujourd'hui, la société numérique et connectée. Les précédentes évolutions de la communication optique ont été majoritairement liées à l'amélioration en termes du traitement du signal, comme par exemple le multiplexage par division de polarisation, qui a pratiquement multiplié par dix le débit de transmission. Le moment est venu de revoir la conception des codes correcteurs et des modulations numériques dans la chaine de communication optique.L'objectif de cette thèse est d'étudier la conception des codes correcteurs et des modulations codées pour la transmission optique tout en s'appuyant sur le concept des codes en graphes sur GF(q), q=2^m. L'originalité de notre approche par rapport à l'état de l'art se trouve dans le fait qu'on se positionnera sur les tailles des alphabets modérées, notamment GF(4) et GF(8), ce qui nous permettrait, sans grande augmentation de complexité, de s'approcher de la capacité de canal et de réduire la taille de l'entrelaceur entre le démodulateur et le décodeur.Le travail effectué se résume en trois contributions principales. La première contribution concerne le schéma de Symbol Interleaved Coded Modulation (SICM) basée sur les modulations de type M-QAM: il est démontré que la QAM-SICM avec q>2 se comporte mieux que la Bit Interleaved Coded Modulation (BICM) et que, dans le cas de q=√M, la SICM atteint la capacité du canal AWGN.La deuxième contribution concerne les codes LDPC réguliers sur GF(q) utilisés dans le schéma QAM-SICM : pour les rendements de code élevés, les codes LDPC 3-réguliers avec des valeurs modérées de q offrent des meilleurs performances que les autres codes LDPC réguliers, considérés dans le cadre de la transmission optique. Finalement, la troisième contribution réside dans la construction d'une nouvelle famille des codes LDPC doublement généralisées sur GF(q), appelés les codes RPP (Repeatition-Parity-Parity), efficaces pour des rendement de code élevés à la fois en terme du seuil asymptotique et de la distance minimale.Transcontinental optical-fiber communication cables play an essential role in data net-working. They enable to transmit huge amount of data at large distances, while respect-ing low-latency transmission constraints. Their design upgrade is an important challenge,given that the optical networks are the backbone of modern Internet. The main evolutionin the optical-fiber transmission in the past has been mainly related to the improvement ofthe signal-processing part of the communication chain, for example the introduction of thepolarization division multiplexing technique has increased the transmission throughput bya factor of ten. Nowadays, it became relevant to reconsider the design of error-controland modulation parts of the optical communication chain.The main goal of this thesis is to investigate the design of error-control codes andcoded modulations for optical communication by using the concept of non-binary graphcodes over GF(q), q= 2^m. The novelty of the approach with respect to the state of artlies in the fact that we are going to consider the codes over moderate alphabet sizes such as GF(4) and GF(8). This would allow us to approach to the channel capacity and toreduce the size of the interleaver between the demodulator and the decoder, at cost of areasonable complexity growth.Our work has lead to three following contributions. The first contribution relates to thescheme of Symbol Interleaved Coded Modulation (SICM) based onM-QAM modulations:it has been demonstrated that the QAM-SICM scheme with q >2 behaves better thanthe traditional Bit Interleaved Coded Modulation (BICM), and that, in the case of q=√M,the SICM scheme achieves the AWGN capacity. The second contribution is focused onregular LDPC codes over GF(q) used within the QAM-SICM scheme: in the context ofhigh-rate codes, 3-regular LDPC codes with moderate values ofqoffer better Bit-ErrorRate (BER) performances than other regular LDPC codes, considered for optical trans-mission. Finally, the third contribution consists in a design of a new non-binary Doubly-Generalized LDPC (DG-LDPC) code family, called RPP (Repetition-Parity-Parity) codes,showing remarkable performances both in terms of the asymptotic decoding thresholdand average minimum, in the interval of high code rates
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
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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