1,720,961 research outputs found
Bounded Error Data Compression and Aggregation in Wireless Sensor Networks
No full text感測節點在實際應用中常常布置於無法供給電力甚至無法進行更換電池的環境，因此如何節省能量消耗以延長感測網路時間成為重要的研究議題。因此，不少失真資料壓縮演算法被提出來，以減少資料傳輸的能量消耗，但這些失真資料壓縮演算法並無法控制誤差大小，難以用在有限誤差的實用問題上，因此本論文將提出有限誤差的資料壓縮演算法，以同時維持良好的資料壓縮率以及有限誤差控制。本研究針對無線感測網路的省電需求，利用資料相關性、時間相關性以及空間相關性等資料特性進行編碼，提出BEDCA (Bounded Error Data Compression and Aggregation in Wireless Sensor Network)。傳統的失真資料壓縮VQ (Vector Quantization)演算法跟DCT (Discrete Cosine Transform)演算法無法控制誤差大小，當容許誤差設定為0.5%，我們的方法可以較其節省至少70%的能量消耗；當容許誤差設定為1.0%，則可以較其節省超過90%的能量消耗。此外，跟 VQ相比，我們方法可以改進20% 壓縮率跟節省62%能量；與DCT相比則可以改進38%壓縮率跟52%能量。經實驗發現，若在傳送過程中就先進行壓縮以及聚合，可比在目的端節點才進行處理節省超過80%以上的能量消耗。本論文針對四種不同屬性的資料進行查詢評估，發現我們的方法之執行結果都較傳統方法為佳。然而時間相關性高的資料，其壓縮率可能會因為誤差的增加反而變差，原因可能歸因於我們所採取的codebook是靜態的，採取動態codebook應可解決此問題。In this paper, an efficient data compression and aggregation method, called BEDCA, is proposed to reduce the size of transmission data under the given bounded error. We first apply the observed transmission data to construct a codebook which is related to the data correlation of the monitoring environment. Given a bounded error, the proposed method determines whether the new sensed data should be compressed or not by comparing it with the reference data such as the previous sensed data (for temporal correlation), the neighboring sensed data (for spatial correlation), and the codebook encoded data (for data correlation). Thus, the total size of transmission data can be minimized for energy saving. We use a real dataset to evaluate the performance of our mechanism. Even if the bounded error is set as a small value (under 0.5%), the proposed method can reduce a lot of the transmission data (over 70%) to cut down the total energy consumption. Our improvement exceeds 90% in the total energy consumed when bounded error is more than 1%. Compared to VQ, our proposed methods can enhance 20% better compression ratio and save 62% energy at least. Our method improve 38% compression ratio and retain 52% energy at least than DCT. Moreover, in our simplified hierarchy model of architecture, more than 20% energy can be saved in any aggregation function in SN than aggregated in sink. Experiment results show that the proposed method can make WSNs more efficient in energy consumption
A Linear-time Heuristic for The Gene Duplication Problem Based on NNI Local Searches
No full text在種系發生學(Phylogeny)上，我們發現基因樹(Gene Tree)和演化樹Phylogenetic Tree)上的不一致，是可能起源於基因流失(Gene Loss)、基因重組(Gene Recombination)、或基因複製(Gene Duplication)。在此情況下，我們希望利用基因複製架構(Gene Duplication Model)，從一群基因樹和一棵演化樹中找出一棵超級樹(Supertree)來表示最有可能演化樹的真正構造。主要計算此超級樹的難處在於基因樹的資料量太大，電腦在計算能力上無法更有效率的找到最適合的超級樹。因此在此篇研究中，我們提出了一個利用最近鄰居交換(Nearest Neighbor Interchange)區域搜尋方法的線性時間啟發式演算法，在現性時間中找到這棵能表現基因樹和演化樹一致性的超級樹。Contradictory phylogenies may result from several effects, such as gene loss, recombination, and duplication. The gene duplication problem is to deduce a most likely phylogenetic supertree from a large set of gene trees with gene duplication information. This problem has beenroved to be NP-complete, and more efficient heuristics are required to deal with large-scale phylogenetic analysis. A naive heuristic which performs a step-by-step search on the tree and recalculate the reconciliation cost on each node is extremely time consuming and requiring enormous computational power. The k-NNI search problem, based on at most k times nearest neighbor interchange operations, has been largely put into use for solving the gene duplicationroblem. In this work, we provide a linear-time solution for the 1-NNI local search problem and an O(p(r + log n))-time heuristic based on 1-NNI local search problem, where p denotes the number of iterations. The result of this work provides a feasible approach for the vasthylogenetic data analysis.1 Introduction 1.1 Gene Tree and Species Tree 3.2 Contribution of This Research 4 Preliminaries 6.1 Basic Definitions and Notation 6.2 The Gene Duplication Problem 7.3 The Local Search Problem 8 Structure Properties 10 The Main Algorithm 15.1 Solving the 1-NNI Local Search Problem in Linear Time 15.2 Heuristic Based on 1-NNI 20 Concluding Remarks 24ibliography 2
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
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