1,720,969 research outputs found
A VI-based measurement system for sharing the customer and supply responsibility for harmonic distortion
No full textOwing to the proliferation of loads which draw nonsinusoidal currents, the current and the voltage distortion in public distribution systems is ever increasing. The usual online investigation methods cannot provide information about the responsibility for harmonic distortion in a given metering section. New methodologies are therefore searched for. Some
recently proposed investigation techniques are recalled in this paper and the relevant measurement problems are discussed.
A digital measurement system which is based on the virtual instrumentation (VI) technique and implements these methods,
is described. The results of some experimental work are also presented
An Automatic Test Equipment for the Calibration of Voltage Transducers
No full textThis paper describes the theory of operation and the design of an automatic test equipment (ATE) for the calibration of voltage transducers in a wide range of frequency. It also discusses the performance of a lab prototype and shows the results of some calibration tests performed by using the ATE proposed
On the characterization of voltage and current transducers in steady-state distorted conditions
No full textThe traceability of measurements performed to gauge information about the operation of electrical power systems under nonsinusoidal conditions is an important and live issue, usually neglected by the technical Standards. A generalized definition of the “composite error” is proposed in this paper as a meaningful index for the metrological characterization of voltage and current transducers in steady-state nonsinusoidal conditions. In this connection, the relationship among the composite error, the classical ratio and phase-angle errors and other parameters characterizing the waveforms of the transduced quantities are pointed out. Finally, problems involved in the measurement of the composite error in steady-state distorted conditions are dealt with and the results of some experimental work are presented
A test system for the evaluation of the expanded uncertainty in DSP-based analysis of bi-tone signals
No full textCharacterization of a VI-based instrument for measurements under distorted conditions and unbalance
No full textCharacterization of a VI-based instrument for measurement under distorted conditions and unbalance
No full text
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
A numerical approach to the evaluation of uncertainty in nonconventional measurements on power systems
No full textThe application of the rules endorsed by the ISO Guide to the expression of uncertainty in measurement (GUM) can turn into a difficult task when quantities that characterize the operation of modern power systems are measured by means of DSP-based instruments.
A numerical approach to easily tackle this task is proposed in this paper, as an alternative to the uncertainty evaluation based on the analytical solution of the uncertainty propagation law, as prescribed by the GUM.
The validity of the numerical approach, which is based on a Monte-Carlo procedure, is first proved in the case of the spectral analysis of a periodic signal, which is the first step for many non-conventional measurements. Then the evaluation of the accuracy of a method for the measurement of the harmonic losses in a power transformer supplying nonsinusoidal load currents is dealt with as an application exampl
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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