1,720,955 research outputs found
Efficient DBA Algorithms for Delay Reduction and Solving the Over-granting Problem of Long Reach PON
No full textThis thesis is submitted to the Department of Electronics and Communication Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electronics and Communication Engineering, December, 2017.Cataloged from PDF Version of Thesis.Includes bibliographical references.The conventional open access optical network (OAN) with point to multipoint structure needs active components to cover large number of users in a wide area. Requirement of more active components significantly increase the network deployment costs. Cover large range congregation of point to multipoint networks is one of the effective solutions to reduce the network deployment costs. This idea offers the long-reach passive optical network (LR-PON) concept with 100 Km spanning the conventional OAN without any active components between sources to destination. However, the LR-PON involves larger propagation delay as well as end-to-end packet delay compared to the conventional PON system, i.e., spanning distance of 20 km. These delays significantly degrade the performances of the LR-PON with the existing centralized dynamic bandwidth allocation (DBA) algorithms. That is why advanced DBA schemes compatible to the LR-PON are required to reduce its longer propagation as well as end-to-end delays. Proper scheduling of the Report and Gate messages is one of the main challenges to design a new DBA algorithm for the LR-PON. Without proper scheduling of the Report and Gate messages, the LR-PON system suffers from over-granting problem. In this thesis, we propose two DBA schemes, i.e., scheme1 and scheme2, for the LR-PON system. The scheme1 is used to reduce the end-to-end packet delay while the scheme2 is used to mitigate the over-granting problem. In the scheme1, the maximum length of a time cycle is subdivided into multiple units called grant processing units and rapidly grants the window size to each optical network unit (ONU). In the scheme2, in the Report message, each ONU sends the frame information instead of total buffer occupancy to avoid the over-granting problem. The combined effect of the scheme1 and scheme2 effectively improves the overall quality of services (QoSs) of the LR-PON system. The performances of the proposed schemes have been evaluated by numerical simulations. The simulation results also have compared with the three existing DBA schemes, i.e., enhance interleaved polling with adaptive cycle time (E-IPACT), multi-thread polling (MTP), and conventional single thread poling (STP), in terms of end-to-end packet delay, bandwidth utilization, over-granting rate, computational
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complexity, and throughput. It shows that the proposed schemes can ensure the enlargement of the LR-PON system with better QoSs.Shuvashis SahaMaster of Science in Electronics and Communication Engineerin
Soliton Dynamics in a Semilinear Dual Core Bragg Grating System with Phase Mismatch
No full textThis thesis is concerned with the dynamics of Bragg grating solitons in a linearly coupled dual-core
system, where Bragg gratings are written on both cores with a phase mismatch, and one core has
Kerr-type nonlinearity, while the other is linear. The investigation starts with the derivation of the
mathematical model, which describes the present system using nonlinear coupled-mode theory.
Phase mismatch between the gratings has been taken into account by considering the random phase
shifts in the gratings. The existence of Bragg grating solitons with zero-velocity (quiescent solitons)
and non-zero velocities (moving solitons) is investigated by systematic linear spectrum analysis. In
the case of quiescent solitons, the system's linear spectrum changes significantly depending on the
zero and non-zero values of the relative group velocity in the linear core c. When c=0, the linear
spectrum shows three disjoint bandgaps, and stationary solutions of the quiescent gap solitons exist
in all bandgaps. However, only the central gap contains the stationary solutions of quiescent gap
solitons for c not equal to 0. The maximum frequency detuning limit within which stationary solutions
of quiescent gap solitons may reside is found in an analytical form. The edge of the central bandgap
always increases with increasing values of phase mismatch, and remains independent of coupling
coefficient, under the maximum phase mismatch condition. In the maximum phase mismatch
condition, no stationary solutions of quiescent gap solitons exist in both upper and lower gaps, as
both upper and lower gaps are merged with the upper and lower branches of the central gap,
respectively
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
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