1,720,955 research outputs found
Data broadcast on multiple wireless channels – Exact and time-optimal solutions for uniform data and heuristics for non-uniform data
No full textThe present chapter reviews the work on the broadcasting problem of N data items over K wireless channels, under the assumptions of skewed data allocation to channels and flat data scheduling per channel. Both the uniform and nonuniform length cases are surveyed showing their exact and heuristic solutions, respectively. For the case of data items with uniform lengths, four exact polynomial time algorithms are presented, all based on dynamic programming. The first algorithm, called DP, takes O(K N^2) time, whereas the second algorithm, called Dichotomic is faster as it runs in O(K N log N) time. The third algorithm is designed for the specific case of K = 2. Although it requires O(N log N) time, and hence it is asymptotically not faster than Dichotomic, it exploits a specific characterization of the optimal solution that
we also use in developing the heuristics for the nonuniform case. Finally, the fourth algorithm, called Smawk-AED has been very recently presented and it takes O(NK) time. This algorithm matches the trivial lower bound for the time complexity of any dynamic programming algorithm for the K-uniform allocation problem that solves all the NK subproblems of allocating a prefix of the items
{1, . . . , n} to k channels, 1 ≤ n ≤ N, 1 ≤ k ≤ K. For the case of data items with nonuniform lengths, the problem is NP-hard when K = 2, and strong NP-hard for arbitrary K. In this latter case, the Optimal algorithm is reviewed.
It requires O(z K N^2) time, where z is the maximum data length, and reduces to the DP algorithm when z = 1. As algorithm Optimal can solve only small instances in a reasonable time, three heuristics are described, all having an O(N(K + log N)) time complexity. All the three heuristics are then tested on benchmarks whose popularities are characterized by Zipf distributions. The experimental tests reveal that one heuristic, called Dlinear, finds optimal solutions almost always, requiring reasonable running times
Classifying matrices separating rows and columns
No full textThe classification problem transforms a set of N numbers in such a way that none of the first N/2 numbers exceeds any of the last N/2 numbers. A comparator network that solves the classification problem on a set of r numbers is commonly called an r-classifier. This paper shows how the well-known Leighton’s Columnsort algorithm can be modified to solve the classification problem of N = rs numbers using an r-classifier instead of an r-sorting network. Overall, the r-classifier is used O(s) times, namely, the same number of times that Columnsort applies an r-sorter. A hardware implementation is proposed that runs in optimal O(s+log r) time and uses an O(r log r(s + log r)) work. The implementation shows that, when N = r log r, there is a classifier network solving the classification problem on N numbers in the same O(log r) time and using the same O(r log r) comparators as an r-classifier, thus saving a log r factor in the number of comparators over an (r log r)-classifier
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
Greedy, Prohibition, and Reactive Heuristics for Graph Partitioning
No full textNew heuristic algorithms are proposed for the Graph Partitioning problem. A greedy construction scheme with an appropriate tie-breaking rule (MIN-MAX-GREEDY) produces initial assignments in a very fast time. For some classes of graphs, independent repetitions of MIN-MAX-GREEDY are sufficient to reproduce solutions found by more complex techniques. When the method is not competitive, the initial assignments are used as starting points for a prohibition-based scheme, where the prohibition is chosen in a randomized and reactive way, with a bias towards more successful choices in the previous part of the run. The relationship between prohibition-based diversification (Tabu Search) and the variable-depth Kernighan-Lin algorithm is discussed. Detailed experimental results are presented on benchmark suites used in the previous literature, consisting of graphs derived from parametric models (random graphs, geometric graphs, etc.) and of "real-world" graphs of large size. On the first series of graphs, a better performance for equivalent or smaller computing times is obtained, while, on the large "real-world" instances, significantly better results than those of multilevel algorithms are obtained, but for a much larger computational effort
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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