Reprints: Recent submissions
Now showing items 441-460 of 548
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Acoustic characterization of a shallow water site
(NATO. SACLANTCEN, 1993/08)Results are presented from an exercise aimed at providing a low frequency active sonar environmental characterization of a specific shallow water site in the Gulf of Mexico. Downward refracting acoustic transmission and ... -
Comparison of measured reverberation on the transmission loss data with modelled results on the West Florida continental shelf
(NATO. SACLANTCEN, 1993/08)Acoustic data from the September, 1992 Area Characterization Test (ACT I) are compared to ADAM (Advanced Development Acoustic Model) output. Conduct of harsh shallow water acoustic exercises, and data interpretation mandates ... -
Shallow-water sound transmission measurements taken on the New Jersey continental shelf
(NATO. SACLANTCEN, 1993/08)Calibrated acoustic measurements were made under calm sea state conditions on the New Jersey shelf near the AMCOR 6010 borehole, a surveyed area with known geophysical properties. The experiment was conducted in 73 m water ... -
Evaluation of experimental techniques for determining the plane wave reflection coefficient at the sea floor
(NATO. SACLANTCEN, 1986/06)One of the most commonly used techniques for determinati on of the geoacoustical properties of the sea bed is the measurement of plane wave reflection coefficients at the ocean bottom. An incident field is pr oduced by ... -
Interface wave studies on the Ligurian shelf usingan OBS array: experimental results and propagation models
(NATO. SACLANTCEN, 1986/06)Seismic waves travelling in the water/sediment or subbottom sediment/sediment interface have been the subject of considerable interest in recent years. Experiments have confirmed the existence of interface waves in different ... -
Considerations relating to the calculation of sound velocity
(NATO. SACLANTCEN, 1971/12) -
Status of ray theory development of Naval Undersea Research and Development Center
(NATO. SACLANTCEN, 1971/12)The first part of this paper discusses NUC (Naval Undersea Research and Development Center) work on the accuracy and validity of ray theory. By comparing the range to convergence zones as indicated by experiment and by ... -
Evaluation of low-frequency bottom backscattering strength vs grazing angle by means of multiple beamforming
(NATO. SACLANTCEN, 1986/06)Bottom backscattering strength was measured in deep water as a function of grazing angle in the Balearic Abyssal Plain of the Mediterranean. The measurements were made with a towed, narrowband low-frequency omnidirectional ... -
Spatial variability of surficial shallow water sediment geoacoustic properties
(NATO. SACLANTCEN, 1986/06)Variability of surficial sediment geoacoustic properties was determined from cores collected at eight shallow-water continental shelf regions in the U.S., Italy and Australia. Highly porous muds found in low energy ... -
Medium-induced low-frequency fluctuations in acoustic transmission loss: examples from measurements in selected geographical areas
(NATO. SACLANTCEN, 1986/06)The ocean is a complex, highly variable acoustic nedium. A propagating acoustic signal is affected by a host of phenomena, including the sea-surf ace and bottom, volume inhomogenei ties, internal waves and tides, and ... -
Directional measurements of low-frequency acoustic backscattering from the seafloor
(NATO. SACLANTCEN, 1986/06)Long-range, low-frequency directional measurements of acoustic backscattering from the seafloor were made in the Tyrrhenian Sea using explosi ve sound sources. The signals were received by a horizontal towed array of ... -
Shear properties of ocean sediments determined from numerical modelling of Scholte wave data
(NATO. SACLANTCEN, 1986/06)Recently it has become apparent that shear properties of ocean sediments are most easily determined from measured propagation characteristics of seismic interface waves. We use a newly developed numeri ca l model of wave ... -
The use of Love waves to determine the geoacoustic properties of marine sediments
(NATO. SACLANTCEN, 1986/06)The importance of the geoacoustic properties of marine sediments for low-frequency shallow water propagation is well established. Reliable compressional properties can be obtained from laboratory analysis of collected ... -
Time dependence of infrasonic ambient seafloor noise on a continental shelf
(NATO. SACLANTCEN, 1986/06)SACLANTCEN is conducting a long term programme of ambient noise measurements that cover the frequency band from 1 to 100 Hz. A sea-bed sensor consisting of three seismometers and a hydrophone has been deployed close to the ... -
Mobile range for measuring ship radiated acoustic noise
(NATO. SACLANTCEN, 1985/01)The Mobile Range described in this paper allows measurements of noise radiated from both surface ships and submarines in open seas with bottom depths from less than lOOm to 400 meters. The range is being developed and built ... -
Mutual coherence and silence
(NATO. SACLANTCEN, 1985/01)In this paper we are developing the theoretical principle of a modification of the acoustical emission by a ship. Its objective is making inefficient the angular measurements achieved by a detector. More precisely, the ... -
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 ... -
Near field propeller radiated noise measurements: model and full scale experimental data comparison
(NATO. SACLANTCEN, 1985/01)The ever rising interest related to the underwater no1se originating from cavitating propellers prompted the Italian Navy to study this aspect of naval architecture in an experimental way. This was accomplished carrying ... -
Some near-field acoustic imaging techniques in noise ranging
(NATO. SACLANTCEN, 1985/01)Acoustical imaging of ship radiating noise sources requires the developrnent of near field array processing. Performance analysis of a linear processing with static sources together with its adaptation to moving sources ... -
Propeller leading edge trimming and maintenance effects on ship's noise operational performance
(NATO. SACLANTCEN, 1985/01)In the last ten years, considerable experience has been gathered at CEIMM's cavitation tunnel (Centra Esperienze Idrodinamiche Marina Militare) on the effects of propeller leading edge geometry on cavitation (and noise) ...