Browsing Technical Reports by Issue Date
Now showing items 201-220 of 322
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A plane-wave decomposition method for modeling scattering from objects and bathymetry in a waveguide
(NATO. SACLANTCEN, 1996/11)In this paper a straightforward plane-wave decomposition method which can be used for solving object andlor interface scattering problems in a waveguide is described. The method utilizes the free-space scattering matrix ... -
Modelling scattering from partially buried cylinders = Acoustic scattering from cylindrical objects embedded between two half-spaces/The computation of the scattered pressure field from a cylinder embedded between two half-spaces = The computation of the scattered pressure field from a cylinder embedded between two half-spaces with different densities
(NATO. SACLANTCEN, 1996/12)1. A boundary integral equation method is presented for the computation of the acoustic field scattered from a cylindrical object which is totally within the water column, totally buried in sediment, or partially buried. ... -
Coupled-mode modelling of acoustic scattering from three-dimensional, axisymmetric objects
(NATO. SACLANTCEN, 1997/01)In this memorandum a coupled-mode method for computing the wavefield scattered by three-dimensional, axisymmetric objects is presented. The method provides a unified approach to solving three-dimensional scattering problems ... -
Scattering by spheres buried in sediment
(NATO. SACLANTCEN, 1997/01)In this report the scattering of acoustic energy by an elastic sphere buried in sediment is examined. The geoacoustic model consists of two homogeneous fluid halfspaces separated by an intermediate layer. The source field ... -
Toeplitz constrained adaptive beamforming with auxiliary data
(NATO. SACLANTCEN, 1997/02)Submarine and mine detection using active sonar face similar problems when adaptive beamforming is required to provide high angular resolution or to suppress angularly isolated interferences. Both -
Channel-sensitive processor: development and detection performance evaluation
(NATO. SACLANTCEN, 1997/03)A Channel Sensitive Processor (CSP) which improves upon the detection performance of the traditional matched filter is developed. This method compensates for the performance degradation of the matched filter due to dense ... -
A towed CTD chain for two-dimensional high resolution hydrography
(NATO. SACLANTCEN, 1997/04)The need for accurate two-dimensional datasets of temperature and salinity in the upper ocean led to the development of a new type of towed chain. Low-cost sensors are moulded in fins and may be randomly placed on the tow ... -
Time-evolution modelling of seafloor scatter: Part 2: experimental verification
(NATO. SACLANTCEN, 1997/04)A time-evolution model of seafloor scatter is numerically implemented and experimentally verified. The model is based on expressing analytically the elementary time-backscattered response of every seafloor surface and every ... -
Time-evolution modelling of seafloor scatter: Part 1: Theory
(NATO. SACLANTCEN, 1997/04)A time-series model for acoustic seafloor backscattering is described. -
Modeling non-Rayleigh reverberation
(NATO. SACLANTCEN, 1997/05)Researchers over the past three decades have experimentally examined non-Rayleigh reverberation, -
RABEL - A program to replay ABEL version 2.2
(NATO. SACLANTCEN, 1997/05)The description of a graphics software tool used to view and manipulate data file is presented. The software is implemented to run in the IDL environment on any platform. RAbel is able to read data from files in the ADAM ... -
The effect of a layer of varying density on high-frequency acoustic reflection, forward propagation loss and backscattering strength
(NATO. SACLANTCEN, 1997/06)This report examines the impact that a thin layer of varying density would have on high-frequency reflection, forward loss and backscattering of acoustic plane waves from the seafloor. A functional form for density ... -
A method to quantify shortfalls and cost benefits for the MO 2015 ASW advanced concepts study
(NATO. SACLANTCEN, 1997/06)An ASW Advanced Concepts Study (ACS) has been initiated as part of Phase 2 of NATO Study, "Implications of New Technology for Maritime Operations in 2015". In this paper, a method to assess ASW search operations is described ... -
RAPID RESPONSE, september 1996: modelling of broadband transmission loss along selected tracks in the Strait of Sicily
(NATO. SACLANTCEN, 1997/07)A large set of experimental acoustic broadband data in the 50-3200 Hz band is analyzed with the objective of deriving average geoacoustic models for three sites in the Strait of Sicily. The experimental data were obtained ... -
SAGA User Manual 2.0: an inversion software package
(NATO. SACLANTCEN, 1997/07)The purpose of many experiments is to identify environmental parameters -
Statistical evaluation of 80 kHz shallow-water seafloor reverberation
(NATO. SACLANTCEN, 1997/09)Knowledge of the background reverberation environment is a prerequisite for the design of any target detection scheme. While the problem of understanding and predicting high-frequency background reverberation level or mean ... -
The ocean wave dynamo: a source of magnetic ambient noise
(NATO. SACLANTCEN, 1997/09)The electromagnetic dynamo field of sea surface waves, a consequence of the Lorentz force, has been measured with two simultaneously operating, closely spaced tri-axial magnetometers. Measurements from a magnetometer located ... -
Very low frequency ambient noise measurements in the Ionian Sea: data report
(NATO. SACLANTCEN, 1997/09)This memorandum describes an experiment and provides a data