1,720,969 research outputs found
Identification of rotating, asymmetry in rotating machines by using reverse directional frequency response functions
No full textA quick and easy but comprehensive identification method for rotating asymmetry in rotating machines is proposed, based on the complex modal testing method. In this work it is shown that the reverse directional frequency response function (reverse dFRF), which indicates the degree of asymmetry, can be identified with a simple testing method requiring only a single vibration sensor and a single exciter. To clarify physical realization associated with estimation of the reverse dFRF, its relation to the conventional frequency response functions, which are defined by the real input (excitation) and output (vibration measurement),: are discussed extensively
Random excitation for modal testing of rotating machinery: Use of modulation technique
No full textOne of the most popular excitation methods for modal testing of rotating machinery is known to be the uncorrelated isotropic excitation, which requires two independent random sources with equal power for generation of a pair of uncorrelated excitation signals. In this work, a new excitation method, the modulated random excitation, is proposed such that a pair of random signals with equal power for modal testing of anisotropic rotors can be effectively generated by modulating the random signal from a single random source with two harmonic carriers of a frequency with 90 degrees phase difference. The real as well as complex approaches are taken to illustrate the effectiveness of the modulation technique. Finally, digital data processing technique is discussed in relation to the implementation of the modulation technique in the discrete time domain, (C) 2000 Academic Press
Pipelined Cartesian-to-polar coordinate conversion based on SRT division
No full textThis brief proposes a new Cartesian-to-polar coordinate conversion technique based on the radix-4 SRT division. The coarse quotient is used to derive the magnitude and the coarse phase by referring to tables, while the fine quotient is applied to linearly interpolate the fine phase to be added to the coarse phase. Compared to the CORDIC-based techniques, the proposed conversion requires less internal word-length and provides parallelism between internal stages, resulting in reduced computation latency and small chip area. A prototype chip designed using 0.25-mu m CMOS technology occupies 0.203 mm(2), and post-layout simulations show maximum frequency of 400 MHz and power consumption of 170 mW at 2.5 V.This work was
supported in part by Institute of Information Technology Assessment through
the ITRC. This brief was recommended by Associate Editor S. Tsukiyama
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
System-level investigation into the regulatory mechanism of the calcineurin/NFAT signaling pathway
No full textCalcineum/nuclear factor of the activated T cell (CaN/NFAT) signaling pathway plays crucial roles in the development of cardiac hypertrophy, Down's syndrome, and autoimmune diseases in response to pathological stimuli. The aim of the present study is to get a system-level understanding on the regulatory mechanism of CaN/NFAT signaling pathway in consideration of the controversial roles of myocyte-enriched calcineurin interacting protein1 (MCIP1) for varying stress stimuli. To this end, we have developed an experimentally validated mathematical model and carried out computer simulations as well as cell-based experiments. Quantitative overexpression and knock-down experiments in C2C12 myoblasts have revealed that MCIP1 functions only as a calcineurin inhibitor. We have also observed a biphasic response of the NFAT activity with increasing stimuli of isoproterenol. Through extensive in silico simulations, we have discovered that the NFAT activity is primarily modulated by ERK5 and MCIP1 under mild isoproterenol stimuli whereas it is mainly modulated by atrogin1 (muscle atrophy F-box protein) under strong isoproterenol stimuli. This study shows that a system-level analysis may help understanding CaN/NFAT signaling-associated disease. (C) 2008 Elsevier Inc. All rights reserved
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
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