1,721,084 research outputs found
Vectorial shearing interferometer with a high resolution phase shifter
No full textVectorial shearing interferometer has been used to measure small and large non-rotationally symmetrical wavefronts aberrations. This interferometric system encompasses large and differential wavefront displacements using a high accuracy rotation system incorporated in a Mach-Zehnder interferometer. The rotation system is based on the Risley prism arrangement and it is controlled with an electronic servomotor system by means of an auto-tuning algorithm. We present the servo-mechanical system, electronic interface and algorithms to control the performance of the high resolution rotation device that is used to control the wavefront phase shifting
Optical current sensor by self-compensating the Faraday effect
No full textA novel optical system that combines a polarimetric current sensor based on the Faraday effect, and a voltage sensor based on the Pockels effect, is described. The proposed device uses polarizers that possess high polarization ratios in specific spectral ranges. This allows the simultaneous codification of current and voltage information in different spectral regions, which, in turn, enables independent measurements of both magnitudes. Validation experiments are presented. " 2009 Society of Photo-Optical Instrumentation Engineers.",,,,,,"10.1117/1.3139299",,,"http://hdl.handle.net/20.500.12104/43379","http://www.scopus.com/inward/record.url?eid=2-s2.0-78149485161&partnerID=40&md5=0e2b3473a53e45282e34abca1c41e63d",,,,,,"5",,"Optical Engineering",,,,"48",,"Scopus",,,,,,"Faraday effect; optical current sensor; optical voltage sensor; Pockels cell",,,,,,"Optical current and voltage sensor using differential spectroscopy",,"Article"
"45159","123456789/35008",,"Beltran, H.C., Electronic Engineering Department, University of Guadalajara, Av. Revolución #1500, CP. 44840, Guadalajara, Jal., Mexico; Flores, J.L., Electronic Engineering Department, University of Guadalajara, Av. Revolución #1500, CP. 44840, Guadalajara, Jal., Mexico; Ferrari, J.A., Instituto de Física, Facultad de Ingeniería, J. Herrera y Reissig 565, 11300 Montevideo, Uruguay; García-Torales, G., Electronic Engineering Department, University of Guadalajara, Av. Revolución #1500, CP. 44840, Guadalajara, Jal., Mexico; Cabrera, J., Electronic Engineering Department, University of Guadalajara, Av. Revolución #1500, CP. 44840, Guadalajara, Jal., Mexico",,"Beltran, H.C
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
Verdet constant dispersion measurement using polarization-stepping techniques
No full textWe present a novel method for measuring the Verdet constant dispersion. The proposed method involves spectral Polarimetrie measurements using three (or more) polarization steps. The procedure has formal similarity with the phase-shifting interferometry (PSI). Thus the Verdet constant in the desired spectral range can be retrieved using well-known PSI algorithms. Validation experiments are presented. � 2008 Optical Society of America
Effect of a herbal growth enhancer feed additive on lamb performance
No full textTwo methods are described for edge enhancement using optical derivative operations. The proposed methods are based on the polarization properties of the twisted-nematic liquid-crystal displays (LCDs). LCDs traduce the image information in changes of the state of polarization of the light, which allows us to generate simultaneously a "positive" and a "negative" (i.e., a contrast-reversed) replica of the digital image displayed on the LCD. In both methods negative and positive replicas are at the same time imagined across a plane. In first case when the negative replica has a lateral differential displacement relative to the original one, an image with enhanced first derivatives along a specific direction is obtained. In the case when the negative replica is low-pass filtered, one obtains the Laplacian of the original image. Unlike the usual Fourier (coherent) image processing, the technique proposed here works with incoherent illumination. Validation experiments are presented. " 2010 SPIE.",,,,,,"10.1117/12.860860",,,"http://hdl.handle.net/20.500.12104/40873","http://www.scopus.com/inward/record.url?eid=2-s2.0-77958149589&partnerID=40&md5=899aea166c745f7edb19b7064ca4b5fb",,,,,,,,"Proceedings of SPIE - The International Society for Optical Engineering",,,,"7797",,"Scopus",,,,,,"Edge enhancement; Image forming; Polarization",,,,,,"Edge enhancement methods based on derivative operations",,"Conference Paper"
"42663","123456789/35008",,"Vélez-Pérez, H., Depto. Electrónica, CUCEI-UDG, Av. Revolución 1500, 44840 Guadalajara, Jalisco, México.; Romo-Vázquez, R.; Ranta, R.; Louis-Dorr, V.; Maillard, L.",,"Velez-Perez, H
- …
