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| Diner, Noel. |
| Models of simulated schools have been used to determine the intrinsic variability in echotraces due to beam pattern effect. This work concerns only morphometric and energetic parameters that can be extracted from echotraces. It appears that dST, the difference between school density and processing threshold is a key parameter, which directly influences the concerned detection angles. Relations, taking into account dST but also, Nbi, the relative school length image compared to the beam width, have been settled for the calculation of length and density corrections. In most cases, corrected values are obtained with errors less than respectively 5% for length and 0.5 dB for density (reverberation index), provided that the Nb-i value is 1.5 or more. When Nb-i... |
| Tipo: Text |
Palavras-chave: Banc de poissons; Détection de poissons; Acoustique; Fish schools; Fish detection; Acoustic. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-546.pdf |
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| Diner, Noel. |
| The aggregate backscattering cross-section, sag, is the sum of backscattering cross-sections of all fish in a shoal. It is a basic acoustical parameter used for shoal description and biomass estimation. Simulations were undertaken for evaluating the impact of horizontal dimension, density, depth and beam width on measurements of sag for shoals with constant abundance. The important factor determining measurement bias is the ratio of shoal size expressed as along cross-section length relative to along ship beam width at mean shoal depth. The results show that 10 log10(sag) is underestimated by about 8 dB for a 5 m long shoal located at 200 m depth if detected by a 7? beam. A formula for correcting sag estimates for shoal sizes bigger than 1.3 times the beam... |
| Tipo: Text |
Palavras-chave: Shoal dimension; Shoal energy; Single beam echosounder; Acoustic measurements; Accuracy; Bias. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2583.pdf |
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| Korneliussen, R; Diner, Noel; Ona, E; Berger, Laurent; Fernandes, P. |
| Acoustic surveys are used to estimate the abundance and distribution of many fish species, and have been based traditionally on data collected at a single acoustic frequency. Although it has been known for some time that the use of additional frequencies can provide information on the nature of the acoustic target, the knowledge and technology required to combine the so-called "multifrequency data" in an appropriate manner has been limited. The use of several transducers of different frequencies is now common on board research vessels and fishing vessels, so multifrequency data are often collected. In order for these data to be combined appropriately, their physical and spatial characteristics from each frequency should be as similar as possible. We detail... |
| Tipo: Text |
Palavras-chave: Species identification; Multifrequency acoustics; Data collection. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-5286.pdf |
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| Le Men, R; Diner, Noel. |
| Au cours de ces premiers travaux la distribution spatiale du champ électrique a été étudiée pour différents types d'électrodes. Afin d'arrêter les caractéristiques exactes du système le plus approprié, il importe de connaître de manière précise le comportement de poissons d'eau de mer soumis à un champ électrique et plus particulièrement celui des espèces auxquelles doit s'appliquer cette technique de pêche. C'est justement l'objet des études définies dans l'annexe scientifique jointe au contrat C.N.E.X.O./I.S.T.P.M. n° 72/454 dont le présent rapport rend compte. OCR NON CONTRÔLE |
| Tipo: Text |
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| Ano: 1974 |
URL: http://archimer.ifremer.fr/doc/1974/rapport-3964.pdf |
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