Reprints: Recent submissions
Now showing items 521-540 of 548
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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 ... -
A general purpose software system for applications in different fields of physics
(NATO. SACLANTCEN, 1979/12)The paper presents the principle of a software system (FTSS) developed by the Danish Defence Research Establishment (DDRE) for applications in different fields of physics. Software is made up by independent modules exchanging ... -
A versatile signal-processing system for producing the angular and frequency distribution of acoustic energy in real time
(NATO. SACLANTCEN, 1979/12)For a number of years the US Naval Research Laboratory (NRL) has been conducting a research program in underwater sound propagation using large aperture hydrophone arrays. This research requires the spectral and angular ... -
Assessment techniques for computer models of sound propagation
(NATO. SACLANTCEN, 1975/10)Computer models of sound propagation have exactly three drawbacks: the model only approximates reality,the computer program only approximates the model, and the cost approximates infinity. The only way to assess these ... -
Computer models for underwater sound propagation
(NATO. SACLANTCEN, 1975/10)The state of affairs of computer models for underwater sound propagation loss estimation is discussed from the viewpoints of two segments of the sonar community; i.e., (1) those who develop the models and are primarily ... -
A technique of comparative analysis of underwater sound transmission loss curves
(NATO. SACLANTCEN, 1975/10)A procedure has been developed for the analysis of transmission loss curves in which received power is known or expressible as a linear function of range. The procedure separates each curve into a sum of three components ... -
Connection between the solution of the Helmholtz and parabolic equations for sound propagation
(NATO. SACLANTCEN, 1975/10)Using a conformal mapping technique in a rectangular waveguide, we present an exact integral relation between the solutions of the Helmholtz equation whose sound speed c(x,y) varies as a function of both depth y and range ... -
Theoretical calculation of transmission loss in the ocean
(NATO. SACLANTCEN, 1971/12)The topic that is dealt with in this paper is a method for c omputation of acoustic transmission loss by sound propagation in the ocean. The method i s based on the ray theory which is used in connection with an acoustic ... -
Deterministic methods of sound field computation
(NATO. SACLANTCEN, 1975/10)Models for acoustic propagation in the ocean environment have matured to a level where they are used routinely to estimate deterministic phenomena and, most recently, have been applied to the investigation of stochastic ... -
Stochastic methods of sound-field computation
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A wave-theoretic method for estimating the effects of internal tides on acoustic wave transmission
(NATO. SACLANTCEN, 1975/10)The effect of the first mode semidiurnal internal tide on a ducttype sound speed profile was approximated by varying the minimum velocity of the parabolic profile in a sinusoidal fashion with a period of 12.42 hours. The ... -
Effect of ship motion on sonar detection performance
(NATO. SACLANTCEN, 1975/10)For an unstabilized transducer, the effect of ship motion on sonar echoes is twofold: 1. Attenuation caused by the rotational movement of the transducer in the vertical plane. The results show that the different loss figures ... -
A solution of of the wave sound equation in shallow water for real speed profiles and solid bottom under sediment
(NATO. SACLANTCEN, 1975/10)The wave equation has been solved by using normal mode theory. The medium is assumed to be horizontally stratified. A closed form solution has been found in the case of GANS - PEDERSEN types of density and sound-speed ... -
Inverse wave propagation in an inhomogeneous waveguide
(NATO. SACLANTCEN, 1975/10)A solution is given for the problem of inverse propagation in an inhomogeneous rectangular two-dimensional waveguide. The sound speed is assumed to vary in depth and inverse propagation means the calculation of the field ... -
Range-dependent normal modes in underwater sound propagation
(NATO. SACLANTCEN, 1975/10)Normal mode theory is best suited for the case of stratified media. Range dependence of the medium properties and of its boundary may nevertheless be taken into account in the framework of an adiabatic approximation provided ... -
Measurements of normal-mode amplitude functions in a nearly-stratified medium
(NATO. SACLANTCEN, 1975/10)In normal-mode treatments of acoustic propagation in nearly-stratified media, calculations are frequently based on the perfectly-stratified medium model, in which symmetry permits separation of the wave equationo In these ... -
Sensitivity of ray theory to input data
(NATO. SACLANTCEN, 1971/12)Acoustic propagation problems which are solved using ray theory require certain input data. In particular, the source and receiver locations, sound-velocity field and bottom and surface conditions are required. Frequently, ... -
Acoustic effects of internal microstructure
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Internal oceanographic microstructure phenomena
(NATO. SACLANTCEN, 1975/10)This paper is concerned with the nature and causes of both fine structure and microstructure in the ocean. Following an account of the acoustic/oceanographic background to subject, the characteristics of fine structure are ... -
Random temperature structure as a factor in long-range propagation
(NATO. SACLANTCEN, 1975/10)A statistical description of horizontal thermal microstructure in anosotropic turbulence is developed for application with an existing acoustic propagation theory. The model predicts a temperature power density spectrum ...