1,721,100 research outputs found
Graphene as a high impedance surface for ultra-wideband electromagnetic waves
No full textThe metals are regularly used as reflectors of electromagnetic fields emitted by antennas ranging
from microwaves up to THz. To enhance the reflection and thus the gain of the antenna, metallic
high impedance surfaces (HIS) are used. HIS is a planar array of continuous metallic periodic cell
surfaces able to suppress surface waves, which cause multipath interference and backward
radiation in a narrow bandwidth near the cell resonance. Also, the image currents are reduced, and
therefore the antenna can be placed near the HIS. We demonstrate that graphene is acting as a HIS
surface in a very large bandwidth, from microwave to THz, suppressing the radiation leakages
better than a meta
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
Micromachined Coplanar Millimeter Wave Band-Pass Filters
No full textIn this paper theoretical, technological and experimental results on a millimeter wave micromachined band-pass filter are presented. The design is based on the image parameters representation of two-port networks, and the device has been realized on a trilayer dielectric membrane. A good agreement between numerical and experimental data has been obtaine
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
Modelling, design and realization of micromachined millimeter-wave band-pass filters
No full textThis paper describes the design, the realization and the experimental characterization of a micromachined band-pass filter with a working frequency of 38 GHz. The synthesis of the structure has been carried out by means of the image parameter representation of two-port networks. A coupled line coplanar configuration has been adopted for the filtering network. The good agreement between theoretical and experimental results demonstrates the validity of the proposed design approach
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
Computer aided design of mm wave circuits fabricated on micromachined silicon
No full textThis paper presents the design methodology for the micromachined circuits operating in the microwave and mm-wave frequency region. The design is based on dividing the circuit into membrane-supported components, bulk components and membrane to bulk transitions. Every region is modeled using appropriate and techniques using full-wave electromagnetic simulation software. As illustrative examples, the design of band-pass filter structures and double-folded slot antenna arrays are briefly described. The micromachined structures were fabricated and measured results are presente
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