In situ beam pattern estimation from seafloor acoustic backscatter measured with swath mapping sonars

2013 ◽  
Author(s):  
Christian De Moustier ◽  
Barbara J. Kraft
Keyword(s):  
Beam Pattern ◽  
Acoustic Backscatter ◽  
Swath Mapping

Characterising Nuclear Simulant Suspensions In Situ With an Acoustic Backscatter System

2013 ◽  
Author(s):  
Jaiyana Bux ◽  
Timothy N. Hunter ◽  
Neepa Paul ◽  
Jonathan M. Dodds ◽  
Jeffrey Peakall ◽  
...  
Keyword(s):  
Storage Tank ◽  
Acoustic Backscatter ◽  
Active Storage ◽  
First Time

In situ characterisation of radiotoxic sludges and slurries is critical to numerous operations including those involving their transport and retrieval. An inexpensive, flexible acoustic backscatter system has been employed for the first time here to a 4/10th scale active storage tank comprising of a nuclear simulant suspension, to verify its application. Intricate suspension characteristics and tank operation features emerged.

Comparison of In Situ Current Measurement Methods, the Accuracy Achieved in the Field and Recommendations for Engineering Design Applications

2018 ◽  
Author(s):  
Gregory Bush ◽  
Carey Nolan
Keyword(s):  
Engineering Design ◽  
Current Data ◽  
Measurement Methods ◽  
Significant Error ◽  
Acoustic Backscatter ◽  
Poor Agreement ◽  
Significant Cost ◽  
Wide Range ◽  
Comparison Data

Here we present a wealth of comparison data from acoustic backscatter current meters against current meters that use an active acoustic path (the RPS CM04). The data cover a wide range of environmental conditions. Very poor agreement between current meters frequently occurs, presenting as both bias and noise. The causes of the differences remain unproven, although for acoustic profilers deployed in deep water, failure of the assumption of the same flow in all beams is a possible source of significant error. As a result of decade’s worth of comparisons plagued with unexplained differences, we have reduced confidence in the accuracy of current data collected by acoustic backscatter sensors. We therefore avoid (where practical) using these instruments when the application of the current data is for engineering design, where uncertainty in accuracy can have significant cost or risk consequences.

scholarly journals Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally

2011 ◽  
Vol 69 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Lucio Calise ◽  
Tor Knutsen
Keyword(s):  
Length Distribution ◽  
Ex Situ ◽  
Target Strength ◽  
Acoustic Backscatter ◽  
Acoustic Measurements ◽  
Acoustic Beams ◽  
Meganyctiphanes Norvegica ◽  
Acoustic Identification ◽  
Made In

Abstract Calise, L., and Knutsen, T. 2012. Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally. – ICES Journal of Marine Science, 69: 119–130. Multifrequency acoustic measurements on ex situ horizontally swimming krill were made in a novel experimental setting. An ensemble of northern krill (Meganyctiphanes norvegica) was introduced to a large enclosure (a mesocosm), and acoustic backscatter was sampled using a multifrequency (70, 120, and 200 kHz) echosounder (Simrad EK60). Two submerged lamps were placed at opposite sides of the mesocosm and switched on and off to induce the krill, by light attraction, to swim horizontally through the acoustic beams. By tracking echoes, animal displacement, swimming speed, and target strength (TS) by frequency were estimated. The dominant and secondary modes of the total-length distribution were 21.8 ± 3.0 and 27.8 ± 2.7 mm, respectively. Although krill orientation was assumed stable and the ping rate was high, the range and inter-ping variability of the average TS values were large, decreasing and increasing with frequency, respectively. The overall TS frequency response observed and concurrent measurements at 120 and 200 kHz confirm the theoretical expectation that the acoustic backscatter from the investigated organisms were confined to the Rayleigh and Geometric scattering regions, a finding that might both aid acoustic identification and size-group separation of in situ northern krill.

scholarly journals Acoustic backscatter by schools of adult Atlantic mackerel

2007 ◽  
Vol 64 (6) ◽  
pp. 1145-1151 ◽  
Author(s):  
Natalia Gorska ◽  
Rolf J. Korneliussen ◽  
Egil Ona
Keyword(s):  
Cross Sections ◽  
Relative Frequency ◽  
Acoustic Properties ◽  
Acoustic Backscatter ◽  
High Frequencies ◽  
Fish Size ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Scattering Spectra

Abstract Gorska, N., Korneliussen, R. J., and Ona, E. 2007. Acoustic backscatter by schools of adult Atlantic mackerel. – ICES Journal of Marine Science, 64: 1145–1151. The extent of acoustic backscatter by schools of adult Atlantic mackerel (Scomber scombrus) is investigated to improve biomass estimates. Previous studies involving modelled scattering from individual mackerel showed that backscattering at high frequencies is dominated by the contribution from the backbone. Accurate predictions of the scattering spectra require consideration of backscattering from the entire skeleton, including details of the bone shapes and their acoustic properties. Here, the backscattering cross-sections from mackerel flesh and backbone are estimated theoretically from 18 to 364 kHz and averaged over fish size and tilt angle, then compared with in situ measurements of volume backscattering from mackerel schools. Based on the comparisons, some gross features of the observed relative frequency response are explained, and recommendations for further studies suggested.

An acoustic backscatter system for in situ concentration profiling of settling flocculated dispersions

2012 ◽  
Vol 27-28 ◽  
pp. 20-27 ◽  
Author(s):  
Timothy N. Hunter ◽  
Jeff Peakall ◽  
Simon Biggs
Keyword(s):  
Acoustic Backscatter

Using a multi-frequency acoustic backscatter system as an in situ high concentration dispersion monitor

2012 ◽  
Vol 80 ◽  
pp. 409-418 ◽  
Author(s):  
Timothy N. Hunter ◽  
Lucy Darlison ◽  
Jeff Peakall ◽  
Simon Biggs
Keyword(s):  
Acoustic Backscatter ◽  
High Concentration

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

Sign in / Sign up

Export Citation Format

Share Document