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Proceedings of acoustics seminar AKUSTIKAN 2
No full textUsing acoustics for biomass evaluation, the back scattering cross section of species has to be determined to convert the data into weighted values. During the cruises of the EU Project "Java Sea Pelagic Fishery", TS measurements on 3 pelagic fishes of economic importance : #Decapterus russelli, #Selar crumenophthalmus, and #Rastrelliger kanagurta$ were carried out, using a BioSonics dual beam echo-sounder at a frequency of 120 kHz. The observations on single or multiple targets in a cage, revealed a large dispersion of the responses, even in the same experiment. These results are discussed and compared with Johannesson's (Anonymous, 1984) in the same area. (Résumé d'auteur
Proceedings of acoustics seminar AKUSTIKAN 2
No full textThe detection and the reverberation measurement of the fish by acoustics allows their behaviour, distribution and structures to be analyzed. All these investigations are mainly based on a relative evaluation of densities. The method of echo-integration also allows the abundance to be quantified. It then necessitates knowing accurately the acoustic performances of the apparatus and the definition of a weight conversion coefficient to apply on the relative data. The Ines-Movies system, used during the acoustic surveys of the PELFISH Project, consists of a calculation procedure with a conversion coefficient. After determination of the #Decapturus russelli$ reverberation index (or TS), in cage this coefficient has been calculated. The accuracy of evaluations resulting from such an index depends particularly on the TS one. But another parameter has to be taken into account ; this is the adjustment of threshold during the prospecting. Even with a controlled adjustment of this latter, the conversion of relative integrated values of the Java Sea shows that the evaluations obtained in this way do not correspond to the richness of the area. According to fishing techniques, the level of commercial Ines-Movies system, allows to better adjust the threshold for evaluation of the targets, taking into account the reverberating surrounding conditions. (Résumé d'auteur
Proceedings of acoustics seminar AKUSTIKAN 2
No full textThe climate in the Javanese basin is a monsoon regime : dry from June to September and humid from November to March. In regions seasonally subject to substantial precipitation, salinity is one of the more important factors affecting the distribution and abundance of fauna. For this reason, stationary vertical profiles have been performed to measure the variations of salinity. These measurements took place during the acoustic surveys carried out in the Java Sea in the framework of the PELFISH Project. Two surveys covering the central part, the first one in October, the second one in February, supply spatial and bathymetric localization of different water masses. Other transects, from Semarang (Central Java) to the Matasiri Islands, all along the north coast of Java, towards the China Sea and on the Kalimantan continental shelf, complete the information. Three factors seem to control the seasonal dynamics of the waters : the local precipitation systems, the direction of the winds, and the disymetric topography of the basin. In the dry season (south-eastern winds), desalinization starts in the North which is less deep. Its progression to the South is made by vertical mixing. In wet season (north-western winds), it is also in the North that the desalinization begins, leading to a temporary inversion of the salinity gradient. The latter will then be restored after the front of precipitation has moved southwards. The return to the dry season leads to a homogenization of salinity. Inter-annual climatic variations seem important and make difficult to have an interpretation based on localized observations in time and space. There is an annual longitudinal gradient where the western part being more steady in salinity than the eastern one, but there is also a latitudinal dissymetry induced by the bathymetry and the northern origin of desalinization. (Résumé d'auteur
Proceedings of acoustics seminar AKUSTIKAN 2
No full textFrom 1991 to 1995, twenty acoustic surveys took place in the Java Sea and the surrounding areas in the frame of the PELFISH Project, sponsored by the European Union, Indonesia and France. Their aim was to study the distribution, abundance and behaviour of the pelagic fauna, especially on the fishing grounds of the seiners. It needed various operations as environmental measurements, echo-integration, TS measurements, school localization, light attraction and trawl samplings. The scientific equipment and its adjustment, as well as the procedures of data acquisition used, are summarized (acoustic and physical measurements, samplings). The spatial, diurnal and bathymetric distribution of the sampling show that the data collection can give accurate information for the prospected area. About 500 environmental stations, 1,500 TS stations and 20,000 density measurements give matter to constitute the basic information of a Data Bank which may be consulted at the RIMF BPPL, Jakarta (INDONESIA) or at ORSTOM, Montpellier (FRANCE). (Résumé d'auteur
Proceedings of acoustics seminar AKUSTIKAN 2
No full textThe coastal borders of northern Java and eastern Sumatra have been prospected during the acoustic surveys, in the depth of about 115 to 50 m, in wet season. The measures of relative density per nautical mile, the vertical distribution of the abundance and shoals have been analyzed. The general characteristics can be drawn-up : they are the extension of an abundant semipelagic fauna occupying the bathymetric strata from 25 to 45 m, and the existence of a dominant pelagic fauna are more coastal. Shoals, low reverberating, are present in all areas but are dominant in the coastal border ; the more reverberating aggregations are more off shore. From the East to the West, their bathymetric localization increases in the sectors near oceanic influences, they are more dense and near the surface. From the East to the West, the abundance of schools and total density decrease. This fact seemingly has to do with the extension of the relatively shallow zone. Two sectors show a particularity : the Bay of Semarang with densities sometimes big, which could be related to the seasonal topography, and the surroundings of the Sunda Strait, zone of passage and exchange for the deep pelagic population. These observations globally confirm the stratification tentative which was carried out during the Workshop of 1994, in specifying the geographical extension of the coastal stratum, very narrow in front of Java, and in proposing that one part of the semipelagic population which constitutes the wealth of the East of Java in dry season, should migrate in wet season towards the slopes of the coastal border. (Résumé d'auteur
Proceedings of acoustics seminar AKUSTIKAN 2
No full textTwo acoustical surveys took place in October 1993 and February 1994, covering the main part of the Java Sea, below a 50 m depth. The echo-integration process was performed through a BioSonics 120 kHz Dual Beam echo-sounder. Fish shoal characteristics and their behavioural aspects were observed. The shoals' configurations were extracted from the echograms and quantified. This information allows the spatial and bathymetric distribution to be presented. An analysis on the abundance and the distribution of shoals is proposed, as well as their contribution to the global clusters and a description of their behaviour during the day and night periods. (Résumé d'auteur
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
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