1,720,991 research outputs found
Comparison of via equivalent circuit model accuracy using quasi-static and full-wave approaches
No full textThe EMC and signal integrity impact of printed circuit board (PCB) trace discontinuities, such as vias, where the signal is transitioned from one layer to another in the PCB stackup, have become significant recently with the use of very high speed signals in today's systems. If these discontinuities are ignored, significant distortion of the high speed signal can occur, and in many cases, cause data errors. A fast and accurate technique to include the effect of via discontinuities in the typical design process is needed to ensure this distortion is considered if significant. Therefore, a simple equivalent circuit for the via discontinuity is needed so that this equivalent circuit can be easily used in the normal signal integrity analysis tools. This paper demonstrates the effect on the equivalent circuit values as the distance between the signal via and the return-current via is increased. Also, the frequency range where a quasi-static based equivalent circuit is accurate or where a full-wave model is required is shown for the various distances between via
Compact Configuration for Common Mode Filter Design based on Planar Electromagnetic Bandgap Structures
No full text"\"A planar electromagnetic bandgap configuration of a compact common mode filter that is laid out on printed circuit board is studied. This filter is used to mitigate the common mode noise traveling on high-speed differential signal traces. These differential signal lines may be connected to I\\\/O connectors and cables and small amounts of common mode noise can result in significant electromagnetic emissions. The filter is obtained by a very simple planar geometry based on the electromagnetic bandgap structures. A cavity made by a rectangular\\\/square patch (together with a solid plane underneath) has a well known and predictable resonant behavior; the coupling between the differential pair routed on top of the patterned plane and the patch cavity, occurring when the traces cross the gap between adjacent patches, is used to reduce the energy associated with the propagation of the common mode noise. The properties of this filter are studied taking into account the layout of a real differential microstrip and the number of gap crossings. A compact configuration is proposed. Time domain simulations validate the suggested layout approach.\"
Feature Selective Validation (FSV) for Validation of Computational Electromagnetics (CEM) – Part II: Assessment of FSV Performances
No full textThe feature selective validation (FSV) method has been proposed as a technique to allow the objective, quantified, comparison of data for inter alia validation of computational electromagnetics. In the companion paper "Feature selective validation for validation of computational electromagnetics. Part I-The FSV method," the method was outlined in some detail. This paper addresses two specific issues related to the implementation of the FSV method, namely "how well does it produce results that agree with visual assessment?" and "what benefit can it provide in a practical validation environment?" The first of these questions is addressed by comparing the FSV output to the results of an extensive survey of EMC engineers from several countries. The second is approached via a case study analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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