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Now showing items 528-547 of 882
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Network-enabled information fusion in support of underwater research
(NURC, 2007/11)Advanced communication and information processing techniques can be applied to underwater research to enable new ways of enhancing real-time experimental outcome. This paper is concerned with three main areas where ... -
New mechanical equipment for handling oceanographic cables
(NATO. SACLANTCEN, 1964/04)The four pieces of equipment described in this report have been designed to facilitate the handling of oceanographic cables by replacing the heavy, and often expensive, equipment at present in use, with lighter, less ... -
The new muesli complexity metric for mine-hunting difficulty in sonar images
(CMRE, 2019/05)A new image complexity metric has been developed that fuses the concept of lacunarity, a measure of pixel intensity variation, with the notion of spatial information, a quantity that captures edge energy. This new metric, ... -
Noise measurements during MAPEX 2000
(NATO. SACLANTCEN, 2002/03)During MAPEX2000 some simultaneous ambient noise measurements with an HLA and satellite SAR images were collected. The aim was to predict shipping and wind noise from the satellite radar and to compare results with acoustic ... -
Noise sources in the ocean - part 1
(NATO. SACLANTCEN, 1975/10)Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ... -
Noise sources in the ocean - part 2
(NATO. SACLANTCEN, 1975/10)Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ... -
NOSC signal processing evaluation laboratory
(NATO. SACLANTCEN, 1979/12)A new acoustic Signal Processing Evaluation Laboratory (SPEL) at the Naval Ocean Systems Center (NOSC), San Diego, is described. This laboratory has been designed to support a broad program of research and development of ... -
Notes on the interpretation of ambient noise statistics
(NATO. SACLANTCEN, 1982/06)Interpretation of statements about the character of ambient sea noise, as well as schemes to measure or model noise, are sensitive to the context or underlying view of what is essentially a stochastic process. A framework ... -
Nowcasting and forecasting of sound velocity structure by ocean modelling
(NATO. SACLANTCEN, 1999/04)The Harvard Ocean Prediction System (HOPS) is applied to an observed oceanographic data set in -
Numerical modeling results for mode propagation in a wedge
(NATO. SACLANTCEN, 1987/11)A PE (parabolic equation) code is used to study propagation in a shallow water wedge with a penetrable bottom. Particular attention is given to "wedge modes" that have wave fronts that are arcs of circles centered on the ... -
Numerical modelling of acoustic scattering by smooth inclusions in a layered fluid-solid medium
(NATO. SACLANTCEN, 1997)A boundary integral equation (BIE) method as descnbed for computing the scattering of a monofrequent acoustic field by a smooth, rigid 30 object in a layered range-independent fluid-solid medium. The BIE is discretized ... -
Numerical simulation of the effects of bathymetry on underwater sound propagation using three-dimensional parabolic models
(NATO. SACLANTCEN, 1998/03)Two different three-dimensional parabolic equation (PE) methods are -
Observations of Mediterranean flow into the Black Sea
(NATO. SACLANTCEN, 1997/10)Mediterranean Sea water inflow into the Black Sea is investigated using acoustic and oceanographic data obtained in the Black Sea exit region. The path of Mediterranean water and the resulting spreading on the continental ... -
Observed sound velocity and temperature profiles in the Strait of Gibraltar during the passage of an internal wave
(NATO. SACLANTCEN, 1966/10)Sound velocity and temperature measurements taken from the sea-surface to 350 m depth, close to one spot over a 24-hour period revealed the passage of an internal wave of approximately 60 m amplitude. The effect of this ... -
Obtaining the ocean index of refraction spectrum from the acoustic amplitude fluctuations
(NATO. SACLANTCEN, 1997)The feasibility of using acoustic measurements to determine the properties of a shallow water internal wave field is investigated through numerical simulations. The random intemal wave field is modeled by a generalized ... -
Ocean currents in the Iceland-Faeroe area, measured by a bottom-mounted ADCP
(NATO. SACLANTCEN, 1992/12)Horizontal currents as a function of depth, measured by a bottommounted -
The ocean noise coherence matrix and its rank
(CMRE, 2019/05)An expression for the cross-spectral density matrix of ocean noise naturally separates into a Toeplitz part and a Hankel part [Harrison (2017). J. Acoust. Soc. Am. 141, 2812?2820]. The Toeplitz part is shown to be substantially ... -
Ocean-basin reverberation from large underwater explosions: part 1: source-level and propagation-loss modelling
(NATO. SACLANTCEN, 1975/10)Predicting the reverberant returns from ocean basin reflectors requires describing acoustic source levels for large, conventional underwater explosions, defining the two way propagation loss and signal spreading from the ... -
Ocean-basin reverberation from large underwater explosions: part 2: computer model for reverberation
(NATO. SACLANTCEN, 1975/10)Following detonation of an underwater explosion, sound reverberates from the ocean surface and bottom and from scatterers within the medium. In addition, the boundaries of the ocean basin and obstructions within it, such ... -
Ocean-bottom reflectivity (a point of view)
(NATO. SACLANTCEN, 1975/10)The analysis procedures for extracting bottom loss values from pulsed acoustic signals that have interacted with the ocean bottom do not inherently consider sub-bottom refraction and reflection of sound, which are important ...