1,720,992 research outputs found
Scalable Production of Light-Sensitive Devices from Liquid-Phase Exfoliated Transition Metal Monochalcogenide Flakes
No full textLayered semiconductors of group, have at- tracted considerable attention in (opto)electronic applications thanks to their atomically thin structures and their (opto)electronic properties. Currently, two-dimensional (2D) indium selenide (InSe) and gallium selenide (GaSe) are emerging as promising candidates for the realization of light-driven thin-field effect transistors (FETs) and photodetectors due to their high intrinsic mobility (10(2) - 10(3) cm(2)V(-1) s(-1)) and their direct bandgap in an energy range (1.3 - 3.2 eV) suitable for UV, visible and NIR light detection. A requirement for large-scale electronic applications is the development of low-cost, reliable industrial production processes. In this context, it has been recognized that liquid-phase exfoliation (LPE) of InSe and GaSe is a cost-effective and environmentally friendly way to formulate inks for FETs, presenting a significant advantage over conventional methods. In this study, printed InSe and GaSe phototransistors are presented showing high responsivity (13 - 274 AW(-1)) and fast response velocity (15 - 32 ms). Furthermore, GaSe phototransistors show an on-off current ratio of similar to 10(3) in the dark, which can be readily achieved without the need for complex design of drain/source contacts or gating techniques. The gate-dependent photoresponse shows that the phototransistors can be modulated by the gate voltage. These results demonstrate that liquid-phase exfoliated InSe and GaSe are valid candidates for low-cost high-performance (opto)electronic devices
Evaluation of a Buckypaper's electromagnetic shielding efficiency in X band
No full textCarbon nanotubes (CNTs) properties and applications are one of the most innovative and interesting research areas in physics and engineering. The electromagnetic behaviour of CNTs composites and plastic material such as PE and PMMA has been analized in several works. Recent works have highlighted how CNTs can be effectively applied in electromagnetic interference (EMI) as high shielding material. Basically, this is due to their high aspect ratio and their tunable conductivity, which allows the electrical percolation (with a little number of CNTs). It is crucial to understand and control the electromagnetic properties of these materials to apply them to devices design in several research fields. A buckypaper is a thin sheet made only with an aggregate of CNTs. A potential application is in shielding technology to protect electronic devices from electromagnetic interferences: for istance CNTs shields could be applied to avoid radar detection of militar aircrafts, or to prevent equipment damaging and unintended setting modication. At the same time, CNTs shields could be applied to avoid radar detection of militar aircrafts. Moreover, in the next years these structures could have a wide application in nano-and bio-science: potential application in the electromagnetical shielding concern nanoelectronis devices, nano-biomedical imaging and sensing or, in the near future, the protect medical equipments from high-frequency radiations. This paper studies the shielding efficiency of a buckypaper interposed between a multifrequency source and a electromagnetic waved detector. Our analysis is focused only on X Band frequencies
Design of wideband antenna for breast cancer detection
No full textIn this work we propose an ultrawideband antenna (UWB) operating in the frequency range between 4.3 - 7 GHz, to demonstrate the potential of this structure in the presence of a breast model. Bandwidth allows this device to have promising behavior in breast imaging with non-invasive techniques
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
A Beamforming Network for 5G/6G Multibeam Antennas Using the PCB Technology
Full text linkThis paper presents the design of a 4×4 Blass matrix for enabling beamforming operations in a four-element uniform linear antenna array (ULAA) operating at 3.5 GHz, corresponding to the first frequency band reserved for the forthcoming fifth and sixth generation (5G/6G) systems. To obtain a simple and inexpensive device, the proposed feeding network, which provides to the ULAA beam pointing capabilities towards four different directions, is entirely implemented using printed circuit board technology. The design procedure is realized adopting an extended iterative mathematical framework accounting for losses control and providing the pointing angles and the matrix coefficients. The performance of the conceived architecture is numerically investigated through full-wave simulations. The versatility, low losses, and low price of the developed microstrip network makes it suitable for both 5G/6G air/terrestrial femtocell base stations and Internet of Things (IoT) cluster-head sensors/actuators
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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