Browsing Reprints by Type "Scientific Report (SR)"
Now showing items 1-20 of 27
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A fast field model for three-dimensional wave propagation in stratified environments based on the global matrix method
(NATO. SACLANTCEN, 1986/03)A three-dimensional fast field program (FFP) model based on the global matrix method will be presented. Compared to traditional propagator matrix methods, the global matrix method allows for a more efficient, and, furthermore, ... -
A theoretical model for the backscattering strength of a composite roughness sea-surface
(NATO. SACLANTCEN, 1974/02)The surface-backscattering strength is calculated according to Rayleigh theory for surface excursions much smaller than the sound wavelength. By taking into account of self-shadowing and modulation of grazing angles, the ... -
Acoustical characteristics of the sea floor: experimental techniques and some examples from the Mediterranean Sea
(NATO. SACLANTCEN, 1974/11)The acoustical properties of the sea floor are primarily determined by the physical properties of the sediments, layering in the sediments, and the roughness of the bottom and sub-bottom. Over the last decade many cores ... -
An evaluation of digitized APT data from the TIROS-N/NOAA-A, -J series of meteorological satellites
(NATO. SACLANTCEN, 1984/03)The TIROS-N/NOAA-A,-J series of meteorological satellites transmit imagery data to the Earth in both digital and analogue formats. The analogue data are a processed subset of the digital dat and have lower resolution. A ... -
Calculation of reverberation and average intensity of broadband acoustic signals in the ocean by means of the RAIBAC computer model
(NATO. SACLANTCEN, 1976/04)Based on the conventional ray-tracing principle, a fast numerical algorithm is developed that calculates averaged propagation loss and reverberation of underwater sound. The averaging is performed by summing incoherently ... -
Deterministic propagation modelling: Part 1: Fundamental principles *Part 2: Numerical results
(NATO. SACLANTCEN, 1981/06)The physics of sound propagation in the ocean is briefly reviewed. The wave equation is presented and a set of solutions under a variety of approximations is discussed. The consistency among these solutions is illustrated. -
High-frequency normal-mode calculations in deep water
(NATO. SACLANTCEN, 1982/10)A method has been developed to perform high-frequency deep-water normal-mode calculations in the multikilohertz region in water depths of the order of 5 km. The results from this technique agree with fast field program ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1974/02)A method is presented for the calculation of sound intensity using only one ray. The sound-velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ... -
Intensity-range relations for shallow-water sound propagation
(NATO. SACLANTCEN, 1976/04)Convincing experimental evidence is presented to show that various "decay laws" for the decrease of sound intensity with increasing range can give high-quality representation for shallow water data. However, while a sequence ... -
Low-frequency ambient noise in the deep sound channel: the missing component
(NATO. SACLANTCEN, 1981/07)There is an important component of the undersea ambient noise which has generally been overlooked or ignored. It is the noise which arrives at a sensor, located in a deep sound channel, by way of ducted sound propagation. ... -
Model for the frequency spread of backscattered underwater sound based on the facet model of the rough sea surface
(NATO. SACLANTCEN, 1978/11)A theoretical model for the doppler spread of backscattered acoustic waves from the rough sea surface is described on the basis of the decomposition of the continuous sea-surface spectrum that leads to the concept of facets. ... -
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 ... -
Range and depth estimation by line arrays in shallow water
(NATO. SACLANTCEN, 1982/01)In shallow water sound propagates in terms of normal modes. The interference between the modes can be utilized to estimate range and depth of an acoustic source in shallow water by applying high resolution power estimators ... -
Review of numerical models in underwater acoustics including recently developed fast-field program
(NATO. SACLANTCEN, 1984/12)Two papers given by SACLANTCEN personnel at the NATO Advanced Research Workshop on Hybrid Formulation of Wave Propagation and Scattering at Castel Gandolfo, Rome, Italy on 30 August to 3 September 1983 are published as a ... -
Some ray and intensity solutions in the complex plane
(NATO. SACLANTCEN, 1974/02)This paper presents a method to test range-dependent ray-tracing programs. The method is based on complex-function theory. From an analytic function that has a zero point at the emitter, expressions for sound speed, ray ... -
Sound propagation in a wedge-shaped ocean with a penetrable bottom
(NATO. SACLANTCEN, 1980/07)Modal cutoff during up-slope propagation in a wedge-shaped ocean is studied using the parabolic equation model; theoretical results are compared with some model tank experiments. -
Sound propagation in shallow water: a detailed description of the acoustic field close to surface and bottom
(NATO. SACLANTCEN, 1982/02)Experimental data are compared with normal-mode predictions for an isovelocity shallow-water propagation channel overlying a complicated layered bottom. Measurements were made close to both the sea surface and the sea floor ... -
Spatial correlation of surface-generated noise in a stratified ocean
(NATO. SACLANTCEN, 1980/10)A model is developed for the calculation of the spatial properties of the noise field produced in a stratified ocean by the action of wind at the surface. The random noise sources are represented by correlated monopoles ... -
Subcritical penetration of narrow Gaussian beams into sediments
(NATO. SACLANTCEN, 1988/03)Complete wave-theory solutions have been obtained numerically for both the reflected and the transmitted fields associated with a narrow Gaussian beam incident on a water-sediment interface near the critical grazing angle. ... -
The optimum frequency of propagation in shallow-water environments
(NATO. SACLANTCEN, 1983/04)The optimum frequency of propagation in shallow water environments is the result of competing propagation and attenuation mechanisms at high and low frequencies. It is shown that the optimum frequency is strongly dependent ...
