Modeling the response from a cascade to an upstream acoustic disturbance

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1322-1330
Author(s):  
Gerald C. Paynter ◽  
Larry T. Clark ◽  
Gary L. Cole
Keyword(s):  
Acoustic Disturbance

Predicting the population consequences of acoustic disturbance, with application to an endangered gray whale population

2021 ◽  
Author(s):  
Elizabeth A. McHuron ◽  
Lisanne Aerts ◽  
Glenn Gailey ◽  
Olga Sychenko ◽  
Daniel P. Costa ◽  
...  
Keyword(s):  
Gray Whale ◽  
Acoustic Disturbance ◽  
Population Consequences

scholarly journals A Minimal Metric for the Characterization of Acoustic Noise Emitted by Underwater Vehicles

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6644
Author(s):  
Giacomo Picardi ◽  
Clara Borrelli ◽  
Augusto Sarti ◽  
Giovanni Chimienti ◽  
Marcello Calisti
Keyword(s):  
Acoustic Noise ◽  
Acoustic Emissions ◽  
Remotely Operated Vehicles ◽  
Underwater Robots ◽  
Acoustic Disturbance ◽  
Marine Fauna ◽  
Acoustic Data

Underwater robots emit sound during operations which can deteriorate the quality of acoustic data recorded by on-board sensors or disturb marine fauna during in vivo observations. Notwithstanding this, there have only been a few attempts at characterizing the acoustic emissions of underwater robots in the literature, and the datasheets of commercially available devices do not report information on this topic. This work has a twofold goal. First, we identified a setup consisting of a camera directly mounted on the robot structure to acquire the acoustic data and two indicators (i.e., spectral roll-off point and noise introduced to the environment) to provide a simple and intuitive characterization of the acoustic emissions of underwater robots carrying out specific maneuvers in specific environments. Second, we performed the proposed analysis on three underwater robots belonging to the classes of remotely operated vehicles and underwater legged robots. Our results showed how the legged device produced a clearly different signature compared to remotely operated vehicles which can be an advantage in operations that require low acoustic disturbance. Finally, we argue that the proposed indicators, obtained through a standardized procedure, may be a useful addition to datasheets of existing underwater robots.

Small disturbances in a conducting fluid in the presence of a current-carrying conductor

1964 ◽  
Vol 60 (2) ◽  
pp. 325-339
Author(s):  
A. M. J. Davis
Keyword(s):  
Uniform Magnetic Field ◽  
Equations Of Motion ◽  
Conducting Fluid ◽  
Alfven Wave ◽  
Displacement Current ◽  
Wave Fronts ◽  
Acoustic Disturbance ◽  
Linear Partial Differential Equations ◽  
A Current ◽  
Small Disturbances

1. Introduction. The problem considered here derives its motivation from a paper by Friedlander (8) on the propagation of small disturbances in a compressible, conducting fluid in the presence of a uniform magnetic field (see also Courant and Hilbert (3), VI, §3a). In this the displacement current and energy dissipation by viscosity, heat conduction and Joule heat are neglected and a system of linear partial differential equations is obtained, which generalizes the equations of motion of the theory of sound. Their solution is in general the superposition of an arbitrary incompressible Alfven wave and a magneto-acoustic disturbance. This latter was considered by constructing a Green's function by means of suitable combinations of plane wave solutions and it was found that there are fast and slow wave fronts diverging from a point disturbance. The latter are conoidal in shape and have a singularity at their vertices which propagate along the field line in either direction from the source.

Acoustically Induced Enhancement of Widening and Fluctuation Intensity in a Two-Dimensional Turbulent Jet

1986 ◽  
Vol 108 (3) ◽  
pp. 331-337 ◽  
Author(s):  
F. O. Thomas ◽  
V. W. Goldschmidt
Keyword(s):  
Turbulent Jet ◽  
Flow Structures ◽  
Jet Flows ◽  
Underlying Structure ◽  
Detailed Data ◽  
Initial Region ◽  
Acoustic Disturbance ◽  
Fine Grained ◽  
Turbulent Plane ◽  
Plane Jet

The enhancement of widening rate and turbulence intensity in a turbulent plane jet, due to an acoustic disturbance are considered. Detailed data at a representative Strouhal number suggest a well organized symmetric structural array in the initial region of the flow. These highly organized flow structures act as efficient agents in the transport of energy to the fine-grained turbulence, leading to greater diffusivity, enhanced turbulence and an increase in widening. The data also suggest significant differences in the underlying structure of the natural and excited jet flows, hence putting in jeopardy any generalization of coherent motions especially excited to facilitate their study.

Good noise, bad noise: A tricky case of balancing risk of physical injury against acoustic disturbance for marine mammals and tidal energy devices

2017 ◽  
Vol 141 (5) ◽  
pp. 3921-3921
Author(s):  
Ben Wilson ◽  
Brett Marmo ◽  
Paul A. Lepper ◽  
Denise Risch ◽  
Steven Benjamins ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Tidal Energy ◽  
Physical Injury ◽  
Acoustic Disturbance ◽  
Energy Devices

Assessing the exposure of animals to acoustic disturbance: Towards an understanding of the population consequences of disturbance

2016 ◽  
Author(s):  
Daniel P. Costa ◽  
Luis A. Hückstädt ◽  
Lisa K. Schwarz ◽  
Ari S. Friedlaender ◽  
Bruce R. Mate ◽  
...  
Keyword(s):  
Acoustic Disturbance ◽  
Population Consequences
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