1,720,969 research outputs found
A Fast Rate-Adaptation Algorithm for Robust Wireless Scalable Streaming Applications
No full textIn this paper we consider a server sending a scalable video stream over a wireless channel to an end-user. We design a fast rate adaptation algorithm which chooses the right transmission policy (video data and associated unequal error protection) based on channel feedback. Our algorithm can be easily implemented as a smart scheduling module at the server side, which adapts its packet selection rules based on the total available channel rate and losses experienced by the end-user. Our simulation results show the good performance of our algorithm compared to the optimal transmission policy, for a wide range of channel conditions. We also identify scenarios that fully benefit from scalable encoding augmented by unequal error protection, compared to traditional bitstream-switching methods based on single stream transmission protected by FEC
Scalable video broadcast in cellular networks: impact on QoS and network resources
No full textBroadcast video streaming represents an important service which will be provided by 4G networks. The current video compression in use, the H.264/AVC (Advance Video Coding), is capable of providing good video quality at substantially lower bit rates than previous video compression standards. The scalable extension of AVC, SVC (Scalable Video Coding), enables a source to transmit a video composed of multiple quality, temporal and spatial sub-streams. The flexibility offered by SVC is appealing for broadcast streaming services, where heterogeneous devices and sets of users are supported. SVC combined with MAC scheduling and the flexibility offered by different modulation and coding schemes provide a novel solution for broadcast streaming services. In this paper, we propose a generic optimization framework to evaluate the performance of the current standard used for streaming services, AVC, and its scalable extension SVC, in terms of wireless utilization, storage requirements and perceived video quality for a single-site transmission scenario. This framework can be implemented on mobile multimedia broadcasting systems, such as ISDB-Tmm [1]. ISDB-Tmm currently considers AVC as video codec, but can be extended to support SVC as well. Selected simulations show the benefits provided by using SVC for broadcast video streaming in a single cell network making use of a flexible MAC layer scheduling. Our study is then extended to a multi-cell network, discussing the issues related to practical deployments
A Resource Allocation Framework for Scalable Video Broadcast in Cellular Networks
Full text linkVideo streaming is one of the most important applications that will make use of the high data rates offered by 4G networks. The current video transport techniques are already very advanced, and the more immediate problems lie in the joint optimization of video coding, AL-FEC, and PHY rate selection with the goal of enhancing the user perceived quality. In this work we provide an analysis of video broadcast streaming services for different combinations of layered coding and AL-FEC, using a realistic LTE PHY layer. Our simulation results show that the scalable content adaptation given by Scalable Video Coding (SVC) and the scheduling flexibility offered by the 3G-LTE MAC-layer provide a good match for enhanced video broadcast services for next generation cellular networks. Our proposed solution is compared to baseline algorithms and broadcast systems based on H.264/AVC streaming solutions. We emphasize the system quality improvement brought by our solution and discuss implications for a wide-scale practical deployment
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
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