1,720,963 research outputs found
PRELIMINARY THERMAL AND ACOUSTIC DESIGN OF SHELTERS FOR HIGH-VOLTAGE ELECTRICAL EQUIPMENT THROUGH NUMERICAL MODELLING
No full textThe constant development of the electric power grid addresses the needs deriving from the growing use of renewable sources and the dispatching flexibility required by mobility electrification. New infrastructures to control the grid parameters and configuration are also being installed in the urban environment, generally enclosed to prevent unauthorised access. Such a solution has positive implications since these shelters must, on the one hand, attenuate the potential noise emitted by the equipment inside and, on the other hand, guarantee enough air changes to avoid overheating of the devices that can compromise the performance and security of high-voltage elements. Hence, cooling and sound insulation must be properly integrated during the design phase of the shelter. This paper presents a feasible, dual and synergetic strategy of acoustic and thermal simulation applicable to the design of a new high-voltage control system. The proposed solution aims to allow adequate heat dissipation from the high-voltage equipment as well as provide smart noise control measures
Mappatura del campo elettromagnetico geneato dalla rete di trasmissione 132/220 kV dell'ASM di Brescia
No full textExperimental evaluation of the limit condition for tap-staggered autotransformers through noise and vibration analysis
No full textThe growing demand for electric energy and the development of green sources such as photovoltaic and wind power are requiring the integration of new systems in the already developed transmission network. This task is not always straightforward, since when a large amount of power is not used, it gives rise to reactive loads. Usually, to put back into phase the voltage and the current, specific devices such as reactors are applied at the electric station level. One of the practices that are becoming increasingly common is the use of two autotransformers adopting the tap-staggering technique. In this way, already existing devices can be used to rearrange the electric line parameters. One of the downsides is that, related to the specific design of the transformers, high magnetic flux can occur in the core. Due to overexcitation, vibrations generated by magnetostriction can become extremely high and can bring to damages that in some cases can cause an impairment of the device. This article aims to find suitable parameters able to predict the approaching of a limit condition beyond which the autotransformer can undergo damage. For this purpose, experimental investigations considering the vibrations and the noise emitted by five autotransformers were carried out in different tap staggering conditions. It was found that the acceleration values very much depend on the position of the transducer, while the acoustic noise measurements give an average of the sound radiated by the different parts of the autotransformers but depend on the distance from the case of the device. For this reason, it is advised not to exceed an average overall value of 80 dB(A) sound pressure level at a 2 m distance from the autotransformer
Design of sound insulating sandwich structures based on multiple criteria
No full textThe pressure on the electric power grid deriving from the growing use of renewable sources and mobility electrification is pushing new infrastructures closer to the urban environment. For this reason, the equipment must be as quiet as possible or otherwise enclosed in technical volumes having the functions to prevent unauthorised access and shield the noise propagating towards the neighbourhood. The different nature of the noise generated by the equipment, together with the other conditions that influence the propagation towards the receivers, require the choice of panels which may differ case by case. For this reason an ad-hoc optimization of the internal structure of the panels may be needed. This article proposes a procedure allowing the selection of the best sandwich structure able to contain the noise on the base of some characteristics such as the weight, the maximum thickness, the cost and the environmental sustainability
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
Thermal and Acoustic Simulation of a Technical Enclosure for High Voltage Control Equipment
No full textThe development of the electric power grid addresses the needs deriving from the growing use of renewable sources and from the dispatching flexibility required by mobility electrification. New infrastructures to control the grid parameters and configuration are also being installed in the urban environment, and the relative equipment must generally be enclosed in technical rooms to prevent unauthorised access. Such enclosures must fulfil two conflicting requirements: on the one hand, they must be closed enough to reduce the potentially disturbing noise emitted by the inner equipment, and, on the other hand, they must feature openings for natural ventilation, as high-voltage elements may get damaged due to overheating. Therefore, cooling and sound insulation aspects must be properly integrated during the design phase, keeping an eye on other potential issues, such as condensation. This paper presents a possible strategy of dual acoustic and thermal simulation applied to the design of a new high-voltage control system that allows the expensive technical equipment to be safeguarded while reducing the risk of noise annoyance
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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