Browsing by Type "Conference Proceedings (CP)"
Now showing items 121-140 of 314
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Flow noise interference in measurements of infrasonic ambient noise
(NATO. SACLANTCEN, 1982/06)Estimates are presented of the local noise generated at infrasonic frequencies by turbulent water flowing in the vicinity of hydrophones used for measurements of ambient noise in the sea. Three situations are discussed: a ... -
Gas bubbles in the sea: a review and model proposals
(NATO. SACLANTCEN, 1975/10)The literature pertaining to both free bubbles (pt 1) and bubbles associated with fish anotomy (pt 2) is reviewed with particular emphasis on their distributions in the sea and influencing factors. An attempt is made to ... -
Geoacoustic modeling of the seabed at higher frequencies
(NATO. SACLANTCEN, 1997)In propagation at higher frequencies, local fluid motion in "hidden coordinate" systems and local discontinuities due to gas bubbles and bioturbation have a perturbing effect on the wave field. To model these effects, a ... -
Geometrical properties of underwater sound propagation
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Graphics for real-time signal-processing systems
(NATO. SACLANTCEN, 1979/12)A graphics software package able to produce hardcopy plots of multi-channel (of the order of 100 channels) data for real-time applications is described. The system is implemented at present using a lineprinter with graphics ... -
Hamiltonian methods in hydro-acoustic propagation
(NATO. SACLANTCEN, 1971/12)The investigation that I wish to outline here originated in the military need of forecasting detection p r obabilities of underwater acoustic emitters, in case s in which only a somewhat general idea of the sound speed ... -
High frequency acoustic observations of Mediterranean flow into the Black Sea
(NATO. SACLANTCEN, 1997)The physical behavior of Mediterranean flow entering the Black Sea through the Strat of Istanbul is described using a variety of high frequency acoustic systems. Because of the density difference between salty Meditermnean ... -
High frequency acoustic propagation in coastal waters
(NATO. SACLANTCEN, 1997)High Frequency Acoustic Propagation experiments were performed with bottom-mounted sources and receivers at different coastal sites. A measurement technique has been developed and propagation loss data have been taken using ... -
High frequency matched field processing
(NATO. SACLANTCEN, 1997)Results are discussed from a high frequency (0 9-5 7 kHz), very shallow water (<10 m) experiment exploring the feasibility of carrying out matched field processing in this frequency and water depth regime The data was ... -
High resolution feature extraction from reverberation data
(NATO. SACLANTCEN, 1997)A new method of signal approximatzon is presented which has the capability to model complex active returns due to reverberation. The method explored herein is data adaptive in the sense that high resolution processing is ... -
High-resolution characterization of seafloor sediments for modeling acoustic backscatter
(NATO. SACLANTCEN, 1997)Quantitative information on fine-scale sediment inhomogeneity is extremely scarce and sorely needed for developing realistic volume scattering models. To address this deficiency, we present a novel approach for sediment ... -
High-speed simulation of an underwater acoustic field using an array processor
(NATO. SACLANTCEN, 1979/12)A computer model PAREQ for simulating the acoustic field of sound propagating in a complicated ocean environment has been installed on a realtime computer system (HP MX21) which includes an array processor (MAP 300). The ... -
Highlights of bottom topography inferred from received depression and bearing angles
(NATO. SACLANTCEN, 1975/10)Statistical properties of the acoustic reflection from the ocean floor have been studied for a var i.ety of bottom types including deep, smooth, flat topography thorough, jagged bottom in shallower (~l km) depths. Explosive ... -
Incidence du bruit acoustique de thoniers ligneurs et senneurs français sur leurs performances de peche
(NATO. SACLANTCEN, 1985/01)Les auteurs présentents quelques expertises acoustiques provenant de deux études réalisées par le GERBAM: - la première, sur 95 thoniers ligneurs pratiquant la pêche du germon (Thunnus alalunga), -la second, sur 18 thoniers ... -
Influence of background-noise spatial coherence on high-resolution passive method
(NATO. SACLANTCEN, 1982/06)New signal processing methods for passive listening have appeared recently : they are called "high resolution" methods because they have theoretically a better resolving power than conventional or adaptive beamforming . ... -
Influence of internal waves on sound propagation in the SOFAR channel
(NATO. SACLANTCEN, 1975/10)In this paper theoretical investigations due to the influence of internal waves to sound propagation in the SOFAR-channel are presented. The undisturbed acoustic field is described by a normal-mode model. The disturbance ...