1,720,963 research outputs found
Maximum Efficiency Point Tracking Scheme for Loosely Coupled Multiple-Receiver Wireless Power Charging System With Mutual Inductance Tracking
No full textThis article presents a maximum efficiency point tracking (MEPT) scheme for a multiple receivers and loosely coupled wireless power charging (WPC) system with a mutual inductance tracking method. In general, the WPC system should satisfy the requirements of constant output voltage and the highest possible efficiency according to sensitive variation of charging environments. To this end, a state-of-the-art MEPT scheme has been studied in this work. Additionally, one of the advantages of the loosely coupled WPC system is the ability to charge multiple devices simultaneously. However, most studies have focused on a single-input and single-output (SISO) system. In this article, we propose a MEPT scheme for a multiple receiver WPC system and a mutual inductance tracking method. The proposed control scheme determines the current of the transmitter based on the mutual inductance between the transmitter and receivers. For validation, the proposed single-input multiple-output (SIMO) WPC system was implemented at 1 MHz using loosely coupled series-series resonant coils and the proposed mutual inductance tracking method. The results verified the performance of the proposed MEPT scheme in a SIMO system regardless of changing charging environments. © 1963-2012 IEEE.
Array Antenna with Suppressed Side Lobe Level for Millimeter-Wave Applications
No full textAs millimeter-wave(mm-wave) band is attracted for 5G. and autonomous driving technology, mm-wave band has become a commercial interest. In mm-wave radar applications, the suppression of the side lobe level has to he considered thoroughly. This paper proposes an array antenna structure that reduces the side lobe level by arranging the equal power divider in series from the uniform distribution structure. The beam patterns of the proposed 1x8 array antenna completely suppress the first side lobe. The level difference between a peak gain and side lobe level was 18.4dB. The proposed method provides an array antenna with low side lobe level for mm-wave radar applications such as motion sensing and security
Pattern Reconfigurable Dual-Polarized Dipole Antenna With Staggered Parasitic Elements
No full textThis paper presents a pattern reconfigurable dual-polarized dipole antenna with staggered parasitic elements operating in 3.5 GHz band. The proposed antenna is designed by assembling two linearly polarized antennas to be orthogonally polarized, and each antenna includes two parasitic elements and a single dipole element. A circuit including a varactor is inserted into each parasitic element, and the current phase of the parasitic element changes according to the capacitance of the varactor. Each antenna has a beam steering range of about +/- 30 degrees in the E-plane, and the beamwidth and gain are maintained uniformly regardless of the steering angle due to the angled parasitic element. Also, because of the continuously changing characteristic of the varactor, the beam of the proposed antenna is steered continuously, and only four varactors are used. The size of the fabricated dual-polarized antenna is 1.40 lambda(0) x 1.40 lambda(0) x 0.47 lambda(0), and the measured results confirm that the antenna has an average gain of around 6 dB with 0.3 dB gain variation.
A Retro-directive Array Antenna with 3-State Phase Shifter for Microwave Power Transfer
No full textIn microwave power transfer system, the large array antennas are necessary and should apply the retro-directive beamforming which is effective in Fresnel region. The retro-directive array antennas requires not only hundreds or thousands antennas but also RF chains. In this paper, for decreasing the cost and complexity of large array antennas, the focusing effect of retro-directive array antenna using low-bit phase shifter is analyzed. Also, a 3-state phase shifter is proposed for effective focusing effect. For testing the proposed antenna, the 16x1 retro-directive array antenna as a test-bed was implemented, and the power transfer were carried out
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
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