scholarly journals Estimating target strength and physical characteristics of gas-bearing mesopelagic fish from wideband in situ echoes using a viscous-elastic scattering model

2021 ◽  
Vol 149 (1) ◽  
pp. 673-691
Author(s):  
Babak Khodabandeloo ◽  
Mette Dalgaard Agersted ◽  
Thor Klevjer ◽  
Gavin J. Macaulay ◽  
Webjørn Melle
Keyword(s):  
Elastic Scattering ◽  
Physical Characteristics ◽  
Target Strength ◽  
Mesopelagic Fish ◽  
Scattering Model ◽  
Gas Bearing

scholarly journals Mesopelagic flesh shear viscosity estimation from in situ broadband backscattering measurements by a viscous–elastic model inversion

2021 ◽  
Author(s):  
Babak Khodabandeloo ◽  
Mette Dalgaard Agersted ◽  
Thor A Klevjer ◽  
Geir Pedersen ◽  
Webjørn Melle
Keyword(s):  
Shear Viscosity ◽  
Spherical Model ◽  
Biological Information ◽  
Target Strength ◽  
Mesopelagic Fish ◽  
Elastic Model ◽  
Acoustic Measurements ◽  
Model Inversion ◽  
Fish Flesh

Abstract In fisheries acoustics, target strength (TS) is a key parameter in converting acoustic measurements to biological information such as biomass. Modelling is a versatile tool to estimate TS of marine organisms. For swimbladdered fish, flesh shear viscosity is one of the required parameters to correctly calculate TS around the resonance frequency, where the target scatters most strongly. Resonance of mesopelagic swimbladdered fish can occur over a range of frequencies and can be within commonly used frequencies (e.g. 18, 38, or 70 kHz). Since there is little information on flesh shear viscosity of fish, especially for mesopelagic species, their resonance can bias the biological information extracted from acoustic measurements. Here, first, the applicability of using a spherical model to estimate resonant backscattering of a generic swimbladder is investigated. Subsequently, a viscous–elastic spherical gas backscattering model is used to estimate the flesh shear viscosity of swimbladdered mesopelagic fish (most likely Cyclothone spp., Family: Gonostomatidae) from in situ broadband backscattering measurements. Finally, the effects of flesh shear viscosity on the TS of swimbladdered mesopelagic fish at 18, 38 (a widely used channel to study mesopelagic layers), and 70 kHz are examined.

Least‐squares inversion of in‐situ sonic Q measurements: Stability and resolution

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 378-385 ◽  
Author(s):  
Aristotelis Dasios ◽  
Clive McCann ◽  
Timothy Astin
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Instantaneous Frequency ◽  
Spectral Ratio ◽  
Full Waveform ◽  
Multiple Measurements ◽  
Sandstone Reservoir ◽  
Gas Bearing

We minimize the effect of noise and increase both the reliability and the resolution of attenuation estimates obtained from multireceiver full‐waveform sonics. Multiple measurements of effective attenuation were generated from full‐waveform sonic data recorded by an eight‐receiver sonic tool in a gas‐bearing sandstone reservoir using two independent techniques: the logarithmic spectral ratio (LSR) and the instantaneous frequency (IF) method. After rejecting unstable estimates [receiver separation <2 ft (0.61 m)], least‐squares inversion was used to combine the multiple estimates into high‐resolution attenuation logs. The procedure was applied to raw attenuation data obtained with both the LSR and IF methods, and the resulting logs showed that the attenuation estimates obtained for the maximum receiver separation of 3.5 ft (1.07 m) provide a smoothed approximation of the high‐resolution measurements. The approximation is better for the IF method, with the normalized crosscorrelation factor between the low‐ and high‐resolution logs being 0.90 for the IF method and 0.88 for the LSR method.

In situ target strength measurements of the scyphomedusa Chrysaora melanaster

2014 ◽  
Vol 153 ◽  
pp. 18-23 ◽  
Author(s):  
Alex De Robertis ◽  
Kevin Taylor
Keyword(s):  
Target Strength

scholarly journals GENESIS AND PHYSICAL CHARACTERISTICS OF THE NEOGENE RED BEDS FROM THE CEDARHILS OF THESSALONIKI, MACEDONIA , GREECE

2018 ◽  
Vol 36 (2) ◽  
pp. 708 ◽  
Author(s):  
A. Tsirambides
Keyword(s):  
Clay Minerals ◽  
Urban Forest ◽  
Clay Fraction ◽  
Eastern Mediterranean Region ◽  
Physical Characteristics ◽  
Coarse Grained ◽  
Red Beds ◽  
Primary Minerals ◽  
In Situ Weathering

The genesis and the physical characteristics of the Neogene red beds of the cedar hills surrounding Thessaloniki are studied in this paper. The peri-urban forest, which covers these hills, has a 3,022 ha area. The topographic relief is smooth and is divided in eight small drainage basins, tapped through small creeks. The elevation of the surrounding hills varies between 85 and 560 m. The dominant land slopes vary between 20 and 55%. All the samples are coarse grained, poorly sorted and friable and present earthy lustre and red colour because of the extensive presence of iron oxides. Angular to sub-angular rock fragments derived from the metamorphic bedrock are very common. Petrographically, the studied red beds belong to the clayey sands. The extended presence (41-66%) of coarse silt and sand size grains (>20 pm) in the samples suggests a mild intensity of in situ weathering of the bedrock. X-ray diffraction analysis of the coarsest fractions 250-20 pm and 20-2 μιτι revealed in decreasing abundance the presence of quartz, feldspars, epidote, micas, chlorite, pyroxenes, amphiboles, and talc. These fractions contain the 2M polytype of mica, while in the fraction <2 pm the 1Μα polytype of illite predominates. In the clay fraction (<2 pm) illite, smectite, and chlorite predominate. The presence of mixed-layer minerals is limited, testifying the almost complete character of hydrolysis of the primary minerals. The formation of red beds took place on low relief land under alternating wet and dry seasons, which prevail in the eastern Mediterranean region since Neogene. The clay minerals are the in situ weathering products of the primary minerals of the greenschists, gneisses and gabbros predominating in the studied area. The extensive presence of clay size grains (11-26%) in the samples, their poor sorting, and their sub-angular morphology, indicate that the red beds are texturally immature. In addition, the abundance of feldspars and Fe-Mg minerals reflects mineralogical immaturity. The low relief and the long-lasting tectonic stability in the Thessaloniki district were essential for the significant thickness of the red beds. The oxygen isotope data of the <0.2 pm fraction (+18.2 to +18.8%o) confirm the pedogenic origin of the clay minerals present. The red beds studied present low plasticity with liquid limit (WÏ) 26.9 to 33.4% and plasticity index (lp) 9.1 to 17.3%. In addition, they have high consolidation index (lc) values (1.03 to 2.28). The swelling potential is low to medium and the activity varies between 0.5 and 1.0. The consolidation and induration degree of the samples analyzed is low, because of the great range of their mineralogical composition and the mild conditions of pressure and temperature to which they have been submitted. The studied red beds are not considered problematic for the foundation of various constructions on them.

scholarly journals The study of the acoustic target strength of Chub mackerel in the northwestern Pacific Ocean in situ

Trudy VNIRO ◽  
2021 ◽  
Vol 184 ◽  
pp. 73-86
Author(s):  
M.Yu. Kuznetsov ◽  
◽  
V.I. Polyanichko ◽  
E.V. Syrovatkin ◽  
I.A. Ubarchuk ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Target Strength ◽  
Northwestern Pacific ◽  
Chub Mackerel ◽  
Northwestern Pacific Ocean ◽  
Acoustic Target

First in situ estimates of acoustic target strength of Antarctic toothfish (Dissostichus mawsoni)

2018 ◽  
Vol 206 ◽  
pp. 79-84 ◽  
Author(s):  
Richard L. O’Driscoll ◽  
Simonepietro Canese ◽  
Yoann Ladroit ◽  
Steve J. Parker ◽  
Laura Ghigliotti ◽  
...  
Keyword(s):  
Target Strength ◽  
Antarctic Toothfish ◽  
Dissostichus Mawsoni ◽  
Acoustic Target

scholarly journals Swimbladder Morphology and Target Strength of a Mesopelagic Fish, Maurolicus japonicus

2009 ◽  
Vol 36 (4) ◽  
pp. 241-249 ◽  
Author(s):  
Tadanori FUJINO ◽  
Kazuhiro SADAYASU ◽  
Koki ABE ◽  
Hideaki KIDOKORO ◽  
Yongjun TIAN ◽  
...  
Keyword(s):  
Target Strength ◽  
Mesopelagic Fish

Diagnosis of dysplasia in Barrett's oesophagus with in-situ elastic-scattering spectroscopy

2000 ◽  
Author(s):  
David C. O. Pickard ◽  
Laurence B. Lovat ◽  
Marco Novelli ◽  
Paul M. Ripley ◽  
Christine Kelly ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Barrett’S Oesophagus ◽  
Barrett's Oesophagus ◽  
Elastic Scattering Spectroscopy

Identification of Marine Soils by Ballistic Penetrometry

1990 ◽  
Vol 112 (4) ◽  
pp. 277-284
Author(s):  
O. Hembise ◽  
P. Guevel ◽  
P. R. Bardey ◽  
J. L. Viaud ◽  
J. Y. Boisson ◽  
...  
Keyword(s):  
High Pressure ◽  
Shape Optimization ◽  
Data Acquisition ◽  
Pressure Sensors ◽  
Physical Characteristics ◽  
In Situ Measurements ◽  
Disposable Sensor ◽  
Course Stability

This article describes a disposable, sensor-filled ballistic penetrator for in-situ measurements during and after penetration into the clayey sediments of the seabed at depths of about 6000 m. The project involved work on several theoretical and experimental aspects of hydrodynamics: penetrator shape optimization, course stability, precision of point of impact. In addition, measurement and data acquisition techniques were developed using high-pressure sensors, and the dynamics of soil penetration and hole-closing were studied. The project led to the implementation of instrument-carrying devices weighing two tonnes, which, by penetrating some 40 m into the clay at impact speeds of the order of 55 m/s, provided valuable information on the physical characteristics of the seabed soils.

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