1,721,047 research outputs found
Realization of a radiometric head for measurements of ultraviolet total erythemal effective irradiance
No full textAn innovative sensor with a spectral response equivalent to the erythemal action curve for ultraviolet total effective irradiance measurements is presented. Optical and sensor components have been selected after the characterization of different samples. The design is based on an innovative interferential filter, which has been realized and tested. A first prototype has been assembled and characterized. Our measurements demonstrate the feasibility and potential of this instrument
Exploring EUV near absorption edge optical constants for enhanced and sensitive grazing incidence reflectivity
No full textA characterization procedures to test multilayers in the EUV and soft X-Ray wavelengths are theoretically studied in this
paper. The fact that most candidate elements have absorption edge energies in the EUV and soft X-Ray has demanded
extensive studies on the optical constants and their possible impact on multilayer design and reflectivity. Thus, EUV and
soft X-Ray multilayers are preliminary designed and tested for various parameters. Effects and impacts of interface
roughness, interlayer thickness, optical constants fluctuations, different phases of interlayer compounds on the
reflectivity of multilayers are investigated in this piece of work. Two theoretical models are used each contributing
different properties of the multilayers. Near absorption edge and off-absorption edge wavelengths are compared and
contrasted to investigate what optical constants near the resonance edges can render in the EUV and soft X-Ray regime.
Almost in all simulations the near absorption edge reflectivity have shown superior sensitivity to fluctuations of various
design parameters. In addition, possible engineering tips of near absorption edge optical constants are indicated
Synthesis of heteroepytaxial 3C-SiC by means of PLD
No full textThin films of silicon carbide (SiC) have been prepared
by means of pulsed laser deposition (PLD) on sapphire
(Al2O3) and Si(100) substrates with a Nd-YAG laser
1064 nm. We achieved the growth of cubic silicon carbide
(3C-SiC) films at the temperatures of 650°C from a SiC
target in vacuum. The as-deposited films are morphologically
and structurally characterized by scanning electron
microscopy (SEM), atomic force microscopy (AFM) and
X-ray diffraction (XRD). The use of off-axis PLD method
placing the sample at 90° with respect to the target leads to
a good quality smooth film
2D Close-Range Navigation Sensor for Miniature Cooperative Spacecraft
No full textThis paper presents the 2D close-range navigation sensor for cooperative spacecraft developed in the framework of the experiment ARCADE. The sensor exploits an infrared LED transmitter mounted on the target, and two photodiode receivers mounted on the chaser. Laboratory tests were performed to assess the sensor performance and range of application. The accuracies of estimates were, on average, 1.9 mm for distance and 1.0 deg for yaw angle, in ranges of [0.20, 0.42] m and [-40, 40] deg, respectively
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
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