1,720,958 research outputs found
First description of the sound pressure and particle velocity components of the ambient noise and boat noise recorded at the WWF- Miramare Natural Marine Reserve (Trieste, Italy)
No full textThe underwater acoustic background noise, and the noise produced by a small outboard-engine boat moving at 6 knots, were recorded in the core zone WWF-Natural Marine Reserve of Miramare waters (Trieste, Italy), an area in which fish density is high, by using a tetrahedron-shaped 4-channels hydrophonic probe placed on the sea bottom.
For the first time, a new 4-channels recording system was employed (“Soundfish”), capable of storing on an SD card, in standard WAV format, the signals coming from the 4 hydrophones.
The collected data have been analyzed by means of the Brahmavolver software, a modification of the software initially developed for Brahma, a 4-channels recorder system developed for aerial applications. As result, vectorial decomposition of the sound field was obtained, containing a set of 4 signals, corresponding the 0th and 1st order spherical harmonics of the sound pressure field. In practice, the 0th-order components is the sound pressure, and the three first-order components are the three Cartesian components of the particle velocity.
Hence, the instantaneous Sound Intensity vector can be computed, from which the three-dimensional direction-of-arrival of the sound can be obtained, and the position of the predominant noise source can be tracked continuously.
A graphical tool such as Surfer TM, was used for charting the vectorial information over a marine map of the area, evidencing the estimated position of the sound source at every instant. This allowed for the construction of the trajectory of a moving sound source, such as a boat. This data can be employed for an analysis of the cause-effect relationship, as at every instant the position of the source, relative to the receiver, is known.
The paper provides a detailed description of the Soundfish recorder, presents the result of a preliminary test of its angular accuracy obtained by experiments conducted inside a large test pool on a automated turntable, explains the mathematical and physical details of the signal processing performed by Brahmavolver, and presents the analysis of the recordings collected at the Miramare Reserve, showing the estimated iso-level contour maps of the boat passages, and, for the first time, statistics about the spatial properties of the sea background noise.
It is also planned to employ the multichannel recordings for making in-air or in-pool playback of the recorded sound, employing a 3D surround loudspeaker system (working following the principle of th Ambisonics method), in order to reproduce the underwater acoustical spatial soundscape recorded in the field, something actually impossible to obtain from mono recordings containing just the sound pressure information
Electric boat underwater radiated noise and its potential impact on species of conservation interest
No full textElectric boats are thought to be noiseless, but in-situ measurements are generally rare. The Underwater Radiated Noise (URN) of 8-m Trimaran Pontoon Boat with two outboard electric engines was measured in the Miramare Marine Protected Area (Trieste, Italy), together with the URN of a fibreglass 5-m boat, with a outboard gasoline engine, for comparisons. International standards and guidelines for shallow waters were considered. URN were provided in one-third octave band and in narrow band spectra. The electric boat produced a low input of underwater noise at low frequencies. Given a low-frequency hearing sensitivity, the listening space reduction (LSR) was lower when generated by the electric than by combustion engine boat for the brown meagre, a local Teleost fish. No difference was found for the bottlenose dolphin LSR although continuous, tonal, high frequency components generated by the electric boat are expected to be highly detrimental for the bottlenose dolphin
Comparing Observed and Theoretical Acoustic Range of the Sciaena umbra Calls in a Marine Protected Area
No full textThis study investigates the acoustic propagation of reproductive calls produced
by the brown meagre (Sciaena umbra) within the Miramare Marine Protected
Area (Gulf of Trieste, Italy). Sound pressure levels recorded along three radial
transects extending from the center of vocal activity were compared with pre-
dictions from transmission loss modeling. The presence of chorusing was
assessed through manual inspection of audio recordings and spectrograms.
Although the shallow coastal environment imposes strong constraints on sound
transmission, choruses were detectable at distances of up to 400 m under low
anthropogenic sound conditions. This detection range, together with the spatial
distribution of calling activity, suggests the presence of multiple aggregations and
supports the hypothesis of lek-like reproductive behavior. Because chorusing is a
reliable proxy for spawning in this Vulnerable species, these findings underscore
the ecological importance of the Miramare MPA in facilitating successful repro-
duction and sustaining long-term population viabilit
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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