CMRE Publications: Recent submissions
Now showing items 781-800 of 882
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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) ... -
Different approaches to economic cruising speeds on a CODOG frigate with due regard to radiated noise
(NATO. SACLANTCEN, 1985/01)All navies, in recent years, have been much more concerned in economic cruising speeds of ships. Frigate type naval ships are usually characterized by two shafts, by multiple propulsion engines per shaft, and by different ... -
Silent ship research applications and operation: proceedings of a conference held at SACLANTCEN on 2-4 October 1984 - volume 2: unclassified papers
(NATO. SACLANTCEN, 1985/01)Introduction: The project to construct an acoustically quiet research ship for the SACLANT ASW Research Centre provided a reason for SACLANTCEN to organize a conference on silent ships, their operation and applications. ... -
The seamount as a noise barrier
(NATO. SACLANTCEN, 1982/06)When the path from a localized noise source is intercepted by a seamount the shielded noise consists of a diffracted component and, if the seamount is close to a sufficiently smooth ocean surface , a multiply-reflected ... -
Effects of topographic blockage and ocean boundaries on low frequency noise fields
(NATO. SACLANTCEN, 1982/06)Low frequency noise in most ocean areas is dominated by shipping or industrial noise. The composite noise field is the result of radiated energy from each discrete noise source propagating over relatively large distances ... -
The prediction of temporal statistics of directional ambient shipping noise
(NATO. SACLANTCEN, 1982/06)A technique for predicting the probability density function (PDF) of the ambient-noise power received by a narrow-band system in a modelled shipping and wind noise field is described. The densities of the shipping noise ... -
Site dependence of wind-dominated ambient noise in shallow water
(NATO. SACLANTCEN, 1982/06)A survey of ambient noise data in shallow water taken under wind-dominated conditions shows substantial differences in spectrum level (often greater than 10 dB) under the same windspeerl and sea-state conditions. This ... -
Site and frequency dependence of ambient noise in the North Eastern Pacific Ocean
(NATO. SACLANTCEN, 1982/06)One-hour averages of omnidirectional ambient noise measurements at 60 Hz and 165 Hz are analyzed for two nearby, deep ocean sites in the Northeastern Pacific during February and March 1981. Site A is a high noise site and ... -
An experimental verification of a geometric acoustic approximation
(NATO. SACLANTCEN, 1971/12)This paper sets out to show that a very simple ray treatment may be used to give a surprisingly good estimate of a sound field, even in conditions where the criteria for the use of geometric acoustics are apparently not fulfilled. -
Detection models and target information processing
(NATO. SACLANTCEN, 1982/06)The passive sonar equation leads in a natural manner to sensor detection performance contours. Useful information can be extracted from observed fractional holding time on non-cooperative targets by use of these contours. ... -
Is power averaging the best estimator for undersea acoustic data?
(NATO. SACLANTCEN, 1982/06)The power average is the statistic which is commonly used in all types of acoustic data processing. It is an excellent estimator for "well behaved" Gaussian distributions when the central or average value is desired. ... -
A parametric examination of some properties of the low-frequency ambient noise field
(NATO. SACLANTCEN, 1982/06)Models for ship-generated ambient noise vary considerably in the detail required of their input data on sources and the environment. This paper describes a model that predicts ambient-noise levels and cumulative distribution ... -
Optimal detection and tracking of acoustical noise sources in a time-varying environment
(NATO. SACLANTCEN, 1982/06)A dynamical detector estimator is derived for nonlinear nongaussian signal processes based on Bucy's representation theorem which is the fundamental result in stochastic filtering. A quantized version of two-dimensional ... -
Performance of three averaging methods for various distributions
(NATO. SACLANTCEN, 1982/06)The performance of three averaging methods, namely the sample median, the sample arithmetic mean, and the sample geometric mean, are analyzed in tenns of their bias, variance, and mean square error. The bias and variance ... -
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 . ... -
A method of estimating the influence of ship's noise on ambient noise measurements
(NATO. SACLANTCEN, 1982/06)Ambient noise measurements are often adversely affected by noise from passing ships. Here, a method is presented which allows the estimation of this influence. The method is especially suitable for shallow water applications. ...