1,721,326 research outputs found
Low depth time reversal modulation technique for ultrasonic guided waves-based communications
No full textUltrasonic guided waves (GWs) have the peculiar capability to travel long distances with minimal attenuation; thus, they represent a compelling alternative which exploits the mechanical waveguide as a form of communication channel and the elastic waves as the signals carrying information. The objective of this work is to implement an effective GWs-based communication system which takes advantage of the channel reciprocity to counteract reverberations and multi-path fading inherent to the dispersive nature of GWs, simultaneously compensating the in-operation mutual interferences between active transducers. More in detail, a strategy based on the Time-Reversal (TR) method is considered, which is combined in an original fashion with a low-depth synthesis of the time-reversed waveforms to be compatible with low-cost switching amplifiers. Experiments performed by simulating the propagation in Aluminum plates suggested that a communication rate up to tenth of kHz can be achieved in presence of highly digitized wave-forms without losing the original information content
Lamb waves Direction of Arrival estimation based on wavelet decomposition
No full textGuided waves in Structural Health Monitoring per-mit to detect different types of damage inside a structure, such as cracks, as well as external impacts. A precise localisation of the damage or the impact point is necessary in order to improve the reliability and accuracy of monitoring approaches. A localisation algorithm based on the estimation of the waves Direction of Arrival (DoA) by means of a DFT-Based Continuous Wavelet Transform decomposition is presented in this work. The approach exploits a multiresolution DFT-Based CWT decomposition applied to the signals acquired by cluster of three piezoelectric (PZT) transducers in 60 degrees configuration. The multiple frequency-based filtering of the signals in the wavelet domain counteracts the complexity caused by the dispersive characteristics of the material. Subsequently the cross-correlation method and the angle estimation are applied for each computed scale. Finally, the Direction of Arrival is computed by an averaging procedure across scales. The approach is validated by means of an experimental setup. The results show the accuracy of the proposed algorithm, enabling to estimate the DoA with an average error of 1.15 degrees and a maximum error of 1.74 degrees
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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