1,725,649 research outputs found
Thermal and Acoustic Design of a Shelter for High-Voltage Electrical Equipment
No full textThe growing demand for electric energy requires smarter and quicker distribution systems. In urban contexts, a smarter distribution of electric power to various classes of consumers, according to their demands, is possible through compact sorters. Since this type of device must be protected from unwanted access by people, wildlife and inclement weather, protection must be placed around the main components. When deployed in urban areas, housing can be built using solid panels. However, there is a risk of overheating the vital and costly parts of the system with the possibility to cause malfunction and, in extreme cases, damage. Moreover, leaving the system open exposes nearby residents to the impulsive noise produced during the operation of the switchgears being part of the system. Hence, there is a need to reach a suitable trade-off between optimal heat transfer and noise propagation. This article attempts to explain the thermal design backed by experimental validation and the noise-spreading modelling necessary to assess the respect of environmental legislation
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
Zeroes of polynomials on definable hypersurfaces: Pathologies exist, but they are rare
Full text linkGiven a sequence {Zd}d?N of smooth and compact hypersurfaces in Rn-1, we prove that (up to extracting subsequences) there exists a regular definable hypersurface ? RPn such that each manifold Zd is diffeomorphic to a component of the zero set on of some polynomial of degree d. (This is in sharp contrast with the case when is semialgebraic, where for example the homological complexity of the zero set of a polynomial p on is bounded by a polynomial in deg(p).) More precisely, given the above sequence of hypersurfaces, we construct a regular, compact, semianalytic hypersurface ? RPn containing a subset D homeomorphic to a disk, and a family of polynomials {pm}m?N of degree deg(pm) = dm such that (D, Z(pm)nD) ~ (Rn-1, Zdm ), i.e. the zero set of pm in D is isotopic to Zdm in Rn-1. This says that, up to extracting subsequences, the intersection of with a hypersurface of degree d can be as complicated as we want. We call these 'pathological examples'. In particular, we show that for every 0 = k = n - 2 and every sequence of natural numbers a = {ad}d?N there is a regular, compact semianalytic hypersurface ? RPn, a subsequence {adm }m?N and homogeneous polynomials {pm}m?N of degree deg(pm) = dm such that bk( n Z(pm)) = adm . (0.1) (Here bk denotes the kth Betti number.) This generalizes a result of Gwozdziewicz et al. [13]. On the other hand, for a given definable we show that the Fubini-Study measure, in the Gaussian probability space of polynomials of degree d, of the set dm,a, of polynomials verifying (0.1) is positive, but there exists a constant c such tha
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
Acoustic performances of triply periodic minimal surfaces fabricated by additive manufacturing: Effects of cell geometry, aspect ratio, and wall thickness
No full textThis work evaluates the acoustic absorption of additively manufactured Triply Periodic Minimal Surfaces (TPMS), focusing on Gyroid and Diamond geometries with varying aspect ratios (AR) and wall thicknesses (WT). Samples were characterized using two and four-microphone impedance tubes, and a test bench for measuring air flow resistivity. Results show that Diamond structures with AR = 0.5 and WT = 0.5 mm achieved almost complete sound absorption (α = 99) at 1185 Hz with a 30 mm sample thickness, outperforming Gyroid geometries. Lower AR values enhanced sound absorption at mid-frequency by increasing tortuosity and decreasing flow resistivity. The non-acoustic parameters retrieved from measurements were used for an inverse characterization based on the Johnson Champoux Allard model. The fitting proved to be very good. These findings provide practical design criteria for optimizing TPMS-based acoustic absorbers in industrial noise control
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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