1,720,973 research outputs found
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
Estimating geodesic barycentres using conformal geometric algebra, with application to human movement
Full text linkStatistical analysis of 3-dimensional motions of humans, animals or objects is instrumental to establish how these motions differ, depending on various influences or parameters. When such motions involve no stretching or tearing, they may be described by the elements of a Lie group called the Special Euclidean Group, denoted SE(3). Statistical analysis of trajectories lying in SE(3) is complicated by the basic properties of the group, such as non-commutativity, non-compactness and lack of a bi-invariant metric. This necessitates the generalization of the ideas of “mean” and “variance” to apply in this setting.
We describe how to exploit the unique properties of a formalism called Conformal Geometric Algebra to express these generalizations and carry out such statistical analyses efficiently; we introduce a practical method of visualizing trajectories lying in the 6-dimensional group manifold of SE(3); and we show how this methodology can be applied, for example, in testing theoretical claims about the influence of an attended object on a competing action applied to a different object.
The two prevailing views of such movements differ as to whether mental action-representations evoked by an object held in working memory should perturb only the early stages of subsequently reaching to grasp another object, or whether the perturbation should persist over the entire movement. Our method yields “difference trajectories” in SE(3), representing the continuous effect of a variable of interest on an action, revealing statistical effects on the forward progress of the hand as well as a corresponding effect on the hand’s rotation.Graduate04050541062
License-free communication using digital mobile radio standards and spread spectrum
Full text linkThe concept of using spread spectrum and open radio standards to provide license-free, short range Peer-to-Peer (P2P) communication is explored. This research makes use of the Time Compression Overlap Add (TC-OLA) algorithm to transparently spread the spectrum of the Digital Mobile Radio (DMR) standard; this allows for reuse of existing hardware, software, and expertise relating to this well established protocol. Initial high level hardware designs of a communication device established the need to implement a proof of concept system which could be validated against Radio Frequency (RF) regulations. This proof of concept system was constructed using a hardware implementation of DMR processed through custom TC-OLA blocks in GNU Radio (GR). A spectral and performance analysis of this system was performed, showing that this approach has several benefits over existing license free communication options.Graduate2020-07-1
Acquisition techniques for direct sequence spread spectrum packet radio systems
Full text linkThe thesis focuses on fast acquisition techniques for spread spectrum packet radio communications systems. Matched filters are often used to achieve fast acquisitions. A new synchronizer using multiple acquisition detection is designed to achieve a highly reliable synchronization with a very simple receiver structure. Since PN codes, in practice, cannot be made too long due to the difficulty of manufacturing long matched filters and the limitation on the bandwidth of the frequency spectrum for the system, the reliable synchronization can be only obtained by repeating the transmission of the acquisition code at the beginning of each packet. The verification or coincidence detection is done by means of a marker detection following an acquisition. A hard-limiting synchronizer is also examined combined with the multiple acquisition detection. The hard-limiting synchronizer is simpler to implement and suitable for receiving signals with a large SNR dynamic range, but it cannot work well when multi-user interference and multi-path interference are present. For this reason, a new linear Automatic Threshold Control (ATC) synchronizer is developed for detecting signals with a large amplitude dynamic range while preserving good performance in multi-path and multi-user interference. The idea of the ATC scheme is to adjust the receiver acquisition threshold level according to the SNR of the received signal such that the largest (or the most likely) correlation peak in a short time period is selected for the synchronization alignment. Therefore false acquisitions caused by strong correlation side-lobes during the acquisition can be eliminated. For the more realistic situation where the multi-user interference or near-far effect causes severe performance degradation, we proposed a novel non-linear multi-user detector or multistage detector which is suitable for both the synchronous and asynchronous CDMA systems. This sub-optimal detector is able to achieve the performance of the optimal detector with very small computation complexity. The near-far effect will no longer exist because the interference from the unexpected users is considered to be not always harmful for the detection of a specific users' message. To apply this detection technique to asynchronous CDMA systems, acquisition for each users' PN codes becomes more critical, because during the acquisition, the information from the other users' PN code is usually not available, which means that acquisition still suffers the near-far effect. The proposed acquisition scheme based on interference cancellation technique and the ATC scheme can alleviate the near-far effect significantly, and provide the necessary condition for the appropriate operations of multi-user detectors.Graduat
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