1,721,007 research outputs found
A Study on Mm-wave Multi-User Beamforming Based on Measurements and Ray Tracing Simulations
No full textThis study concerns the evaluation of the impact of the radio channel on beamforming performance in Multi-User indoor environment at mm-Wave band of 70GHz, using both wideband measurements and Ray Tracing simulations
Database simplification for field prediction in urban environment
No full textThe performance and the usability of deterministic field prediction tools for the urban environment is heavily limited by the high computing time, which depends exponentially on the size of the input urban database. A simple technique for urban database simplification, aimed at speeding up deterministic field prediction is presented in the paper. Such a technique, based on a sort of heuristic preprocessing of the city map, identifies the buildings which are 'likely' to have an impact on the multipath propagation mechanism taking place between the radio terminals, and discards the rest of the map. Using this pre-processing technique, the CPU time can be decreased by orders of magnitude in typical ray tracing prediction cases, while the accuracy of the results only marginally degrades, as shown in the results section of the paper
Electromagnetic and System level Co-simulation for RFID Radio Link modeling in Real Environment
No full textThe recent widespread diffusion of radio-frequency identification (RFID) applications operating in the UHF band have been supported by both the request for greater interrogation ranges and larger and faster data exchange.
UHF-RFID systems, exploiting a physical interaction based on Electromagnetic propagation, introduce many problems that have not been explored (or only partially) for the previous generations of RFID systems (e.g. HF). Therefore, the availability of reliable tools for modelling and evaluating the radio-communication between Reader and Tag within an RFID radio-link are needed. The paper discuss the impact of real environment (e.g. Electromagnetic Coupling, Multipath propagation) on system performance in terms of error-probability and received powers, showing some relevant effects and trade-offs in transponder and reader design
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
Interleaved-MIMO DAS for Indoor Radio Coverage: Guidelines for Planning
Full text linkThe combination of distributed antenna systems (DAS) and multiple input multiple output (MIMO) schemes opens the way to a variety of coverage solutions for indoor environment. In this paper interleaved-MIMO (i-MIMO) DAS indoor coverage extension strategies are studied. Their performance in high-order MIMO cases is investigated in realistic conditions through LTE-A link-level simulations, based on statistical data extracted from radio channel measurements; the impact of the deployment strategy on performance is then evaluated and useful planning guidelines are derived to determine the optimum deployment for a given propagation environment
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
Path-Loss Statistical Model for Urban Mobile Backhauling at mm-frequencies
No full textIn order to meet the unceasing demand for greater data-rates, future cellular
network will be deployed according to heterogeneous layouts, with traditional
macro-cellular sites acting as umbrella for a multitude of underlain micro-cells.
Backhauling communications will likely rely on point-to-point wireless links not
always in clear line of sight. A path loss model for urban backhauling at mmfrequencies
is presented in this work, based on a Monte Carlo approach applied
to a proper statistical description of the environment
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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