1,720,971 research outputs found
Dual Frequency MIMO Rectenna with Two-Branch Rectifier and Common Power Storage Unit
No full textA dual-frequency (433 MHz and 2.45 GHz) circularly polarized MIMO rectenna with dual-branch rectifier and a common power management unit is presented. For the lower frequency a dual-layer, four-element, monopole antenna array is implemented. The four monopoles are oriented along the perimeter of a square and are fed with 90° phase difference resulting in a circularly polarized antenna array. The total covered area is 80 x 80 mm2, and the maximum gain is 2.45 dBi. For the 2.45 GHz antenna, an elliptical patch is used implementing it in the middle of the square substrate that is used for the 433 MHz monopoles. As a result of the close proximity of the two radiating elements, the gain of the patch is enhanced to 6.2 dBi. Both antennas are probe-fed with two coaxial cables that pass through the antenna substrates. The coaxial cables are connected on the dual-branch, dual-frequency rectifiers. For the matching networks of the rectifiers, lumped elements are used for the 433 MHz rectifier, and hybrid, distributed and lumped elements, are used for the ISM band voltage-doubler. The combined use of both frequencies results in RF-to-dc efficiency up to 70% for input power close to 0 dBm. The dual rectifiers have a common load since they are terminated with a common power management unit circuit. The commercially available e-peas AEM30940 RF is considered as the PMU circuit. It presents cold start-up from 380 mV and 3 μW, and is able to supply low-voltages (from 1.2 to 1.8 V) suitable for most microcontrollers and also “high” voltages ranging from 1.8 V up to 4.1 V
A Hybrid RFID/Localization Antenna with HIS and 3D-Printed Inclusions
No full textThe need for tracking and localizing items/people through energy autonomous devices suggests the combined exploitation of Ultra High frequency (UHF) to supply power and Ultra Wideband (UWB) signals for communication. This paper proposes the design and implementation of a versatile antenna to fulfil those requirements. The one-port spiral-dipolecombination achieves the insensitivity to the background scenario through the presence of a High Impedance Surface (HIS) able to simultaneously guarantee unique performance, still maintaining a low-profile stack-up: no back-radiation in the entire frequency range, circular polarization in the UWB band, and high efficiency in the UHF one. The use of 3D-printing reveals to be strategic for the robustness of the structure and for the adopted feeding mechanis
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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