1,720,966 research outputs found
Path Filters: A Class of True Inline Topologies with Transmission Zeros
No full textIn this article, we present a comprehensive discussion of a new class of inline microwave filters with transmission zeros in the response, namely, the path filters. The main features of this filters class are highlighted, and an original (synthesis-based) design approach is presented, relying on the derivation of suitable characteristic polynomials. In addition to the classical generalized Chebyshev characteristic, two new characteristics are introduced (namely, the bounded Chebyshev and the reduced Chebyshev), which allows improving the flexibility in the requirements assignment of path filters. A new method for the synthesis of the low-pass prototype is also introduced, which overcomes the limitation in the classical synthesis based on the manipulation of the transversal prototype (whose synthesis may fail in case of path filters). Finally, the proposed approach for designing the class of considered filters has been validated by several examples that include the evaluation of the characteristic polynomials, the prototype synthesis, and the dimensioning of the physical structures in waveguide technology
A True Inline Coaxial-Cavity Filter with Two Symmetric Zeros
No full textThis work deals with the design of true inline filters with two symmetric transmission zeros. A new filters category named 'path filters' is introduced (including the considered filters), its general features are discussed and analyzed and a general method for the synthesis of the low-pass prototype network is proposed. To validate the proposed design approach, a coaxial-cavity filter with a true inline topology exhibiting two symmetrical transmission zeros has been designed and fabricated. The realized prototype shows a response in good agreement with the theory
Extended Path Filter Configurations
No full textIn this work we introduce a method for increasing the maximum number of transmission zeros in the response of path filters. This recently introduced inline filter configuration allows for up to four transmission zeros on the imaginary axis. The solution proposed in this work, while maintaining the inline configuration, increases the number of transmission zeros up to N-1 (with N order of the filter). The novel concept allowing the additional zeros introduction is verified by means of the design of a waveguide filter of order 8 with 6 transmission zeros
De-embedding of filters in multiplexers via rational approximation and interpolation
No full textIn this article, we present a method to recover electrical parameters of filters embedded in a multiplexer for which scattering measurements are given. Unlike other approaches proposed for this problem, this method does not require a priori knowledge of the scattering parameters of the junction. This feature renders the procedure well suited for tuning purposes or for fault diagnosis. Technically, the algorithm starts with a rational approximation step, to derive a rational representation of certain scattering parameters of the multiplexer. This representation is then used in a second step to identify an electrical model of each filter. This second step relies on a rational interpolation technique used to extract the filter's responses
System identification of microwave filters from multiplexers by rational interpolation
No full textMicrowave multiplexers are multi-port structures composed of several two-port filters connected to a common junction. This paper addresses the de-embedding problem, in which the goal is to determine the filtering components given the measured scattering parameters of the overall multiplexer at several frequencies. Due to structural properties, the transmission zeros of the filters play a crucial role in this problem, and, consequently, in our approach. We propose a system identification algorithm for deriving a rational model of the filters’ scattering matrix. The approach is based on rational interpolation with derivative constraints, with the interpolation conditions being located precisely at the filters’ transmission zeros
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
- …
