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Usama Kadri
Recent analysis of data, recorded on March 8th 2014 at the Comprehensive Nuclear-Test-Ban Treaty Organisation's hydroacoustic stations off Cape Leeuwin Western Australia, and at Diego Garcia, has led to the development of an inverse model for locating impacting objects on the sea surface. The model employs the phase velocity of acoustic-gravity waves that radiate during the impact, and only considers their propagation in the water layer. Here, we address a significant characteristic of acoustic-gravity waves: the ability to penetrate through the sea-bottom, which modifies the propagation speed and thus the arrival time of signals at the hydrophone station...
January 29, 2019: Scientific Reports
Zhiwang Zhang, Ying Cheng, Xiaojun Liu
Topological valley-contrasting physics is attracting increasing attention because of its potentials as a promising information carrier in electrics and classical systems. In this work, we reveal the valley-Hall effect and the valley projected edge states in two-dimensional sonic crystals with modulated acoustic honeycomb lattice. The sonic crystals are arranged by soft-material rods and thereby in a sub-wavelength scale, of which the lattice constant is only 0.267 times the wavelength and can be modulated to almost 0...
November 14, 2018: Scientific Reports
Moses A Ajemigbitse, Fred S Cannon, Mark S Klima, James C Furness, Chris Wunz, Nathaniel R Warner
Unconventional oil and gas residual solid wastes are generally disposed in municipal waste landfills (RCRA Subtitle D), but they contain valuable raw materials such as proppant sands. A novel process for recovering raw materials from hydraulic fracturing residual waste is presented. Specifically, a novel hydroacoustic cavitation system, combined with physical separation devices, can create a distinct stream of highly concentrated sand, and another distinct stream of clay from the residual solid waste by the dispersive energy of cavitation conjoined with ultrasonics, ozone and hydrogen peroxide...
November 1, 2018: Environmental Science. Processes & Impacts
Nian Xu, Bin Zhu, Fang Shi, Ke Shao, Yanfu Que, Weitao Li, Wei Li, Wenjing Jiao, Hua Tian, Dongmei Xu, Jianbo Chang
Monitoring dynamic distribution is crucial to conservation management of anadromous sturgeons, but traditional survey methods are less efficient for low-density populations in a large river. Natural propagation of Chinese sturgeon has been monitored annually mainly at the spawning ground using netting for eggs and hydroacoustics for broodstock. However, absence of spawning was observed sporadically in recent years, indicating further crises for the declining population. We analyzed eDNA of water samples collected from 24 sites across 1360 km of the migratory route of anadromous Chinese sturgeon in the middle and lower reaches of the Yangtze River...
October 10, 2018: Die Naturwissenschaften
Stephan Hilgert, Cristovão Vicente Scapulatempo Fernandes, Stephan Fuchs
In the context of reservoirs, sediment trapping, and aquatic greenhouse gas (GHG) production, knowledge about the distribution of hot and low spots is essential for improved measurement strategies. It is also a key to a precise assessment of the GHG emissions of each reservoir. Large numbers of reservoirs are used mainly for hydroelectric power generation and, hence, affected by strong changes in water level. Drawdown events may lead to significant changes in spatial sediment and organic carbon distribution and, consequently, strongly alter the GHG emission patterns of the water body...
January 1, 2019: Science of the Total Environment
Paul A Brandner, James A Venning, Bryce W Pearce
Cavitating and bubbly flows involve a host of physical phenomena and processes ranging from nucleation, surface and interfacial effects, mass transfer via diffusion and phase change to macroscopic flow physics involving bubble dynamics, turbulent flow interactions and two-phase compressible effects. The complex physics that result from these phenomena and their interactions make for flows that are difficult to investigate and analyse. From an experimental perspective, evolving sensing technology and data processing provide opportunities for gaining new insight and understanding of these complex flows, and the continuous wavelet transform (CWT) is a powerful tool to aid in their elucidation...
August 13, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Ann E A Blomberg, Thomas C Weber, Andreas Austeng
Natural seepage of methane into the oceans is considerable, and plays a role in the global carbon cycle. Estimating the amount of this greenhouse gas entering the water column is important in order to understand their environmental impact. In addition, leakage from man-made structures such as gas pipelines may have environmental and economical consequences and should be promptly detected. Split beam echo sounders (SBES) detect hydroacoustic plumes due to the significant contrast in acoustic impedance between water and free gas...
June 25, 2018: Sensors
Pablo H Vigliano, Magalí M Rechencq, María V Fernández, Gustavo E Lippolt, Patricio J Macchi
Habitat use in relation to the thermal habitat availability and food source as a forcing factor on habitat selection and use of Percichthys trucha (Creole perch), Oncorhynchus mykiss (rainbow trout), Salmo trutta (brown trout) and Salvelinus fontinalis (brook trout) were determined as well as future potential thermal habitat availability for these species under climate change scenarios Representative Concentration Pathways 4.5 and 8.5. This study was conducted in three interconnected lakes of Northern Patagonia (Moreno Lake system)...
September 15, 2018: Science of the Total Environment
M Loher, T Pape, Y Marcon, M Römer, P Wintersteller, D Praeg, M Torres, H Sahling, G Bohrmann
Submarine mud volcanoes release sediments and gas-rich fluids at the seafloor via deeply-rooted plumbing systems that remain poorly understood. Here the functioning of Venere mud volcano, on the Calabrian accretionary prism in ~1,600 m water depth is investigated, based on multi-parameter hydroacoustic and visual seafloor data obtained using ship-borne methods, ROVs, and AUVs. Two seepage domains are recognized: mud breccia extrusion from a summit, and hydrocarbon venting from peripheral sites, hosting chemosynthetic ecosystems and authigenic carbonates indicative of long-term seepage...
April 19, 2018: Scientific Reports
Milan Muška, Michal Tušer, Jaroslava Frouzová, Tomáš Mrkvička, Daniel Ricard, Jaromír Seďa, Federico Morelli, Jan Kubečka
Understanding spatial distribution of organisms in heterogeneous environment remains one of the chief issues in ecology. Spatial organization of freshwater fish was investigated predominantly on large-scale, neglecting important local conditions and ecological processes. However, small-scale processes are of an essential importance for individual habitat preferences and hence structuring trophic cascades and species coexistence. In this work, we analysed the real-time spatial distribution of pelagic freshwater fish in the Římov Reservoir (Czechia) observed by hydroacoustics in relation to important environmental predictors during 48 hours at 3-h interval...
March 29, 2018: Scientific Reports
R Showen, C Dunson, G H Woodman, S Christopher, T Lim, S C Wilson
Results are presented of a demonstration of real-time fish blast location in Sabah, Malaysia using a networked hydroacoustic array based on the ShotSpotter gunshot location system. A total of six acoustic sensors - some fixed and others mobile - were deployed at ranges from 1 to 9 km to detect signals from controlled test blasts. This allowed the blast locations to be determined to within 60 m accuracy, and for the calculated locations to be displayed on a map on designated internet-connected computers within 10 s...
March 2018: Marine Pollution Bulletin
J P Egerton, A F Johnson, J Turner, L LeVay, I Mascareñas-Osorio, O Aburto-Oropeza
Hydroacoustic technologies are widely used in fisheries research but few studies have used them to examine the effects of Marine Protected Areas (MPAs). We evaluate the efficacy of hydroacoustics to examine the effects of closure to fishing and habitat type on fish populations in the Cabo Pulmo National Park (CPNP), Mexico, and compare these methods to Underwater Visual Censuses (UVC). Fish density, biomass and size were all significantly higher inside the CPNP (299%, 144% and 52% respectively) than outside in non-MPA control areas...
January 15, 2018: Scientific Reports
Grigory I Dolgikh, Sergey S Budrin, Stanislav G Dolgikh, Vladimir V Ovcharenko, Vladimir A Chupin, Sergey V Yakovenko
The paper analyzes the experimental data obtained in a comprehensive experiment aimed at identifying the regularities of transmitted hydroacoustic signal transformations at the shelf of decreasing depth. The 33 Hz harmonic hydroacoustic signals were generated at the shelf of the Sea of Japan by a low-frequency source. Distribution of the transmitted energy at vertical sounding from the surface to the bottom was studied at different shelf points with Bruel & Kjaer 8104 hydrophone. At the shore, the transformed seismo-acoustic signals were received by a 52...
October 2017: Journal of the Acoustical Society of America
Usama Kadri, Davide Crivelli, Wade Parsons, Bruce Colbourne, Amanda Ryan
Analysis of data, recorded on March 8th 2014 at the Comprehensive Nuclear-Test-Ban Treaty Organisation's hydroacoustic stations off Cape Leeuwin Western Australia, and at Diego Garcia, reveal unique pressure signatures that could be associated with objects impacting at the sea surface, such as falling meteorites, or the missing Malaysian Aeroplane MH370. To examine the recorded signatures, we carried out experiments with spheres impacting at the surface of a water tank, where we observed almost identical pressure signature structures...
October 24, 2017: Scientific Reports
Sébastien Sollberger, Bernhard Wehrli, Carsten J Schubert, Tonya DelSontro, Werner Eugster
We monitored CH4 emissions during the ice-free period of an Alpine hydropower reservoir in the Swiss Alps, Lake Klöntal, to investigate mechanisms responsible for CH4 variability and to estimate overall emissions to the atmosphere. A floating eddy-covariance platform yielded total CH4 and CO2 emission rates at high temporal resolution, while hydroacoustic surveys provided no indication of CH4 ebullition. Higher CH4 fluxes (2.9 ± 0.1 mg CH4 per m2 per day) occurred during the day when surface water temperatures were warmer and wind speeds higher than at night...
October 18, 2017: Environmental Science. Processes & Impacts
Roman Baran, Tomáš Jůza, Michal Tušer, Helge Balk, Petr Blabolil, Martin Čech, Vladislav Draštík, Jaroslava Frouzová, Asanka D Jayasinghe, Ievgen Koliada, Tomáš Mrkvička, Milan Muška, Daniel Ricard, Zuzana Sajdlová, Lukáš Vejřík, Jan Kubečka
For ethical reasons and animal welfare, it is becoming increasingly more important to carry out ecological surveys with a non-invasive approach. Information about fish distribution and abundance in the upper water column is often fundamental. However, this information is extremely hard to obtain using classical hydroacoustic methods. We developed a rigid frame system for pushing upward looking transducers of the scientific echo sounder (38 and 120 kHz) in front of the research vessel. The efficiency of the new approach for monitoring juvenile fish at night was investigated by comparing the results with a quantitative fry trawl in the Římov Reservoir in the Czech Republic...
July 6, 2017: Scientific Reports
Haley A Viehman, Gayle Barbin Zydlewski
The natural variation of fish presence in high-velocity tidal channels is not well understood. A better understanding of fish use of these areas would aid in predicting fish interactions with marine hydrokinetic (MHK) devices, the effects of which are uncertain but of high concern. To characterize the patterns in fish presence at a tidal energy site in Cobscook Bay, Maine, we examined two years of hydroacoustic data continuously collected at the proposed depth of an MHK turbine with a bottom-mounted, side-looking echosounder...
2017: PloS One
David Grimardias, Jean Guillard, Franck Cattanéo
Sediment flushings of hydropower reservoirs are commonly performed to maintain water resource uses and ecosystem services, but may have strong impacts on fish communities. Despite the worldwide scope of this issue, very few studies report quantitative in situ evaluations of these impacts. In June 2012, the drawdown flushing of the Verbois reservoir (Rhône River) was performed and subsequent impacts on the fish community were assessed, both inside the reservoir (fish densities by hydroacoustic surveys) and downstream (short-term movement and survival of radio tracked adult fish)...
July 15, 2017: Journal of Environmental Management
Kevin D Heaney, Mark Prior, Richard L Campbell
The ocean is nearly transparent to low frequency sound permitting the observation of distant events such as earthquakes or explosions at fully basin scales. For very low frequency the ocean acts as a shallow-water waveguide and lateral variability in bathymetry can lead to out-of-plane effects. In this paper, data from the International Monitoring System of the Comprehensive Test Ban Treaty Organization (CTBTO) is used to present two cases where robustly localized seismic events in locations clearly within the two-dimensional (2-D) shadow of a continent or large island generate T-phase signals that are received on a hydro-acoustic station...
February 2017: Journal of the Acoustical Society of America
Wenya Linda Bi, Ryan Brewster, Dennis Poe, David Vernick, Daniel J Lee, C Eduardo Corrales, Ian F Dunn
Superior semicircular canal dehiscence (SSCD) syndrome is an increasingly recognized cause of vestibular and/or auditory symptoms in both adults and children. These symptoms are believed to result from the presence of a pathological mobile "third window" into the labyrinth due to deficiency in the osseous shell, leading to inadvertent hydroacoustic transmissions through the cochlea and labyrinth. The most common bony defect of the superior canal is found over the arcuate eminence, with rare cases involving the posteromedial limb of the superior canal associated with the superior petrosal sinus...
December 2017: Journal of Neurosurgery
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