1,721,285 research outputs found
A power filter for the detection of burst events based on time-frequency spectrum estimation
No full textWe propose as a statistic for the detection of bursts in a gravitational wave interferometer the 'energy' of the events estimated with a time-dependent calculation of the spectrum. This statistic has an asymptotic Gaussian distribution with known statistical moments, which makes it possible to perform a uniformly most powerful test (McDonough R N and Whalen A D 1995 Detection of Signals in Noise (New York: Academic)) on the energy mean. We estimate the receiver operating characteristic (ROC, from the same book) of this statistic for different levels of the signal-to-noise ratio in the specific case of a simulated noise having the spectral density expected for Virgo, using test signals taken from a library of possible waveforms emitted during the collapse of the core of type II supernovae
Performance of a 'generalized delta-filter' for the detection of burst events
No full textIn this work we report on the performance of a complete implementation of the generalized delta filter detector for burst events, tested against simulated data. We measure the receiver operating characteristics in the case of noise having the expected spectral density of the Virgo interferometer, injecting test signals taken from the Zwerger–Müller library of simulated events, predicted to result from the collapse of type II supernovae, for different levels of signal to noise ratio
Study of the corrosion behaviour of AA5083 aluminium samples subjected to ECAP and cryogenic treatment
No full textIn this work the corrosion behaviour of AA5083 aluminium alloy (Al-Mg), initially subjected to a heat treatment of solubilization (380°C for 1h) and then to a severe plastic deformation (SPD), through the Equal Channel Angular Pressing (ECAP), was studied. Some samples were subjected to cryogenic treatment before the ECAP process. The aim of this experimentation was to carry out an electrochemical characterization of the aluminium alloy, evaluating the influence of grain refinement obtained by ECAP and of solubilization and cryogenic treatments on the corrosion behaviour of the material. The analysis of the corrosion resistance of the different samples was performed at room temperature by means of electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy tests) in an aqueous solution at 0.1 M Cl- at pH 2. The experimental results show that in these conditions, the corrosion behaviour of the different samples is more or less the same and consequently neither the cryogenic treatment nor the refinement produced by ECAP influence the corrosion resistance of the alloy
Study of the localized corrosion resistance of AA5083 aluminium alloy subjected to severe plastic deformation
No full textIn this work the localized corrosion behaviour of AA5083 aluminium alloy, subjected to severe plastic deformation (SPD) through the Equal Channel Angular Pressing technique (ECAP), useful to obtain an ultrafine microstructure, was studied. This process improves mechanical properties and modifies the microstructure of the alloy. With more details, the localized corrosion resistance of the AA5083 alloy subjected to thermal and cryogenic treatments and finally to ECAP was evaluated. Electrochemical characterization of this alloy was performed in aqueous solution 0.1 M of NaCl and pH 6.5, at room temperature, by means of cyclic potentiodynamic polarizations and potentiostatic polarizations for evaluating metastable pitting events. All tests were performed in deaerated conditions. The experimental results show that ECAP tends to increase AA5083 alloy localized corrosion susceptibility
The SU (2) deconfinement phase transition with zymanzik action
No full textA simulation of the SU(2) theory at finite temperatures by means of a Symanzik improved action is presented. The asymptotic scaling properties are discussed, based on an accurate measurement of the deconfinement temperature. The asymptotic scaling violation pattern is found to be substantially equivalent to the one already observed in studies using the Wilson action. An analysis using an effective coupling shows a precocious scaling, which we interpret as an effect of the Symanzik improvement. © 1994
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
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