1,720,991 research outputs found
Sensitivity and mode spectrum of a frequency-output silicon pressure sensor
No full textThe vibrational mode spectrum of a silicon vibrating pressure sensor is investigated. Particular attention is given to the analysis of the vibration shapes, quality factors and relative sensitivity of the resonance frequencies as a function of pressure. It is shown that a pressure sensitivity of a few parts per million at one atmosphere can be achieved. Some comments are also made regarding an improved design of the device
In-line polarizers and filters made of metal-coated tapered fibers: resonant excitation of hybrid plasma modes
No full textIn-line single-mode-fiber (SMF) filters and polarizers require the interaction of electric fields which, in principle, are essentially confined to the fiber core. The reduction of the core and cladding diameters in a tapered fiber cause the evanescent field to extend beyond the outer boundary. Thus, when a metal film is evaporated on a tapered fiber, the surface plasma modes cause coupling to the fiber mode. Our experimental and theoretical results demonstrate that such coupling leads to the resonant excitation of surface plasma modes and allows for the design of filters, polarizers, and sensors
Cylindrical metal-coated optical fibre devices for filters and sensors
Full text linkNovel fibre-optic components suitable for sensor applications and wavelength filters are reported. The devices consist of a tapered fibre whose uniform waist has been coated with a thin layer of gold. The operation principle is the resonant excitation of a surface plasma mode of the metal film
Novel in-line fiber-optic filters and polarisers
No full textNovel in-line devices, based on a tapered fiber whose uniform waist has been metal-coated, are reported. The resonant excitation of a surface plasma mode of the metal film allows for the design of wavelength filters and polarisers
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
Ultraselective and broadly tunable optical bandpass filter using a fibre grating and a Fabry-Perot
No full textWe report on an ultraselective (170 MHz bandwidth) and widely tunable (>100 GHz) optical bandpass filter based on the use of a structure composed of a fibre Fabry-Perot and a fibre grating: The first experimental demonstration of the filter operation is presented and a range of tuning of several hundreds of GHz can be achieved by using the presented techniques
Array factor of a phased array antenna steered by a chirped fiber grating beamformer
No full textIn this letter, we present the array factor of a phased array antenna driven by a chirped fiber Bragg grating. The phase and the amplitude of a microwave modulating signal have been measured from the light reflected by the grating and the radiation pattern of an eight element antenna has been computed from the phase and amplitude distributions. The principal lobe radiated by the array can be steered without squint error between ±30° in the frequency range 2-6 GHz
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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