1,721,184 research outputs found
Determination of Spectral Focusing Features of a Metamaterial Slab
No full textThe realization of flat superlenses is a major application area of metamaterials. A slab of double negative (DNG) material is capable of imaging with a resolution below the diffraction limit. The focusing quality depends primarily on the amount by which the original spectrum of the source is restored behind the lens. Even a small deviation from the ideal case limits the spectrum of the transmitted field, which may result in a significant degradation of the focusing quality. In this work we determine the width of the transmitted spectrum as a function of the configuration parameters and establish a relation between the spectrum width and the imaging quality. Restrictions imposed on the focusing characteristics and difficulties arising in full wave simulations will be pointed out
Numerical analysis of focusing by a metamaterial lens
No full textOver the last several years there has been a surge of interest in artificial materials because of their potential to expand the range of electromagnetic properties in materials. The so called metamaterials, also known as left-handed (LHM) or double-negative (DNG) materials with negative permittivity
and permeability have attracted growing interest. An important application area is the realization of flat superlenses with imaging properties beyond that of conventional lenses. This work investigates the focusing properties of a lossless planar DNG slab with a relative permittivity and permeability both approaching the value -1. The relation between the imaging quality and the material parameters is examined both analytically and numerically. Results obtained from numerical simulations via the transmission line matrix method are compared to the analytical solution
Novel Frequency-Domain and Time-Domain Techniques for the Combined Maxwell–Dirac Problem in the Characterization of Nanodevices
No full textThis book gives a compact overview about actual research in the field of Electromagnetics and Network Theory and its Microwave Applications. It contains aspects on antennas and wave propagation, microwave- and communication-systems and methods for the numerical modeling of components, networks and structures being part of these systems.
An actual state of research in antennas and propagation is given as well as wave propagation in RF-lines and electric networks which are crucial for the investigation of microwave systems like radar-, radio-location- and communication- systems.
Especially in mobile applications, radar- , radio-location- and navigation- systems as well as
microwave sensors are more and more in use. Therefore an actual state of research in this field is given. Actual results of research on such systems are shown for automotive
radar, a high precision radio-location-system, RF-sensors and RF-measurement technologies.
The wide field of communication systems is further discussed where an overview
about progress in mobile communication and wireless data transmission is given and
results of actual research are shown. At last, actual numerical methods are discussed which are essential for the estimation of electromagnetic effects in all the applications shown previously. In the scope between the treatment of very tiny structures and very large structures new ways are shown for the numerical modeling of the electromagnetic field in nanostructures as well as in macrostructures and large periodic structures. The book is dedicated to Prof. Dr. Dr. hc. Peter Russer and his research work which is shown in his autobiography.
Content Level » Professional/practitioner
Keywords » Antenna - Devices and Circuits - Electric field modelling - High-Frequency Engineering - MIMO - Modelling of MEMs - Peter Russer
Related subjects » Computational Science & Engineering - Electronics & Electrical Engineering - Optics & Laser
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
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