Technical Reports: Recent submissions
Now showing items 61-80 of 322
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Single ping clutter reduction: segmentation using Markov random fields
(NATO. SACLANTCEN, 1999/03)The use of low frequency active sonar in shallow water leads to large numbers of clutter detections. This high false alarm rate can overload automatic tracking and classification algorithms. Traditional detection algorithms ... -
A neural-network-fusion architecture for automatic extraction of oceanographic features from satellite remote sensing imagery
(NATO. SACLANTCEN, 1999/06)This report describes an approach for automatic feature detection from fusion of remote sensing imagery using a combination of neural network architecture and the Dempster-Shafer (DS) theory of -
Performance assessment of propagation models in AESS-6.0
(NATO. SACLANTCEN, 1999/08)A set of AESS propagation-loss predictions has been generated for typical operational scenarios in both deep and shallow water, for two sonar frequencies (500 and 3500 Hz) and for several source-receiver combinations. ... -
Spectral integral representations of scattering from volume inhomogeneities
(NATO. SACLANTCEN, 1999/07)In-situ measurements of scattering strength can be obtained by analyzing the early-time, high angle reverberation from bottom and sub-bottom features. In order to provide insight into the mechanisms which cause bottom ... -
The magnetic dipole moment of RV Alliance
(NATO. SACLANTCEN, 1999/02)A SACLANTCEN magnetometry sea trial was performed in September 1998 in the northern Tyrrhenian Sea in the vicinity of the Formiche di Grosseto islands. One of the trial objectives -
Broad-band geoacoustic inversion in shallow water from waveguide response measurements on a single hydrophone: theory and YELLOW SHARK experimental results
(NATO. SACLANTCEN, 1999/05)Executive summary: Performance models such as the Allied Environmental Support System (AESS) require environmental input parameters such as the geoacoustic properties of the battlespace. The models ingest the input parameters ... -
Scintillation instrument for remote environmental analysis (SIREN)
(NATO. SACLANTCEN, 1999/02)A high frequency acoustic propagation instrument which was developed to study ocean variability in the Strait of Istanbul (Bosporus) is described. The scintillation instrument for remote environmental analysis (SIREN) was ... -
Nowcasting and forecasting of sound velocity structure by ocean modelling
(NATO. SACLANTCEN, 1999/04)The Harvard Ocean Prediction System (HOPS) is applied to an observed oceanographic data set in -
A classification technique combining aspect dependence and elastic properties of target scattering
(NATO. SACLANTCEN, 1999/04)Discrimination between man-made and natural underwater objects and between man-made objects of different characteristics are the key objectives of target classication. The current approach is mainly based on the analysis ... -
Measurements of acoustic scattering from partially and completely buried spherical shells
(NATO. SACLANTCEN, 1999/04)Recent work at NATO SACLANT Undersea Research Centre has concentrated on investigating the use of low frequency sonars (2-20 kHz) in order to better exploit scattering features of buried targets that can contribute to their ... -
A review of the application of UUV technology to mine countermeasures
(NATO. SACLANTCEN, 1999/03)The emphasis on littoral warfare, the proliferation of low cost mines available to potentially hostile countries, high exercise costs and risks related to the operation of present NATO MCM units, require the development ... -
Drifter and float observations in the Adriatic Sea (1994-1996): data report
(NATO. SACLANTCEN, 1998/12)During the period December 1994 to November 1995, 62 Argos tracked surface drifters, one Argos tracked drifter drogued to 300 m and 3 Argos tracked sub-surface floats were released in the Adriatic Sea to describe the ... -
Distributions of magnetic field variations, differences and residuals
(NATO. SACLANTCEN, 1999/02)Temporal and spatial variations of the geomagnetic field were recorded in different geographic areas, -
Improvements to data networks in support of REA during Generic Oceanographic Array Technology (GOATS) 98
(NATO. SACLANTCEN, 2000/05) -
High resolution geoacoustic inversion in shallow water: a joint time and frequency domain technique
(NATO. SACLANTCEN, 1998/12)High resolution geoacoustic data are quired for accurate predictions of -
Bottom reverberation in shallow water: coherent properties as a function of bandwidth, waveguide characteristics and scatterer distribution
(NATO. SACLANTCEN, 1998/10)Scattering physics are often modeled using the Helmholtz equation for computational reasons. Likewise, propagation loss to and from scattering regions are often treated in a like manner. The usual approach for generating ... -
Deployable underwater surveillance systems(DUSS): localization and fusion of multistatic contacts: evaluation of feasibility using experimental data
(NATO. SACLANTCEN, 1998/12)Active sonar deployable underwater surveillance systems (DUSS) are based on a distributed network -
Decay of large underwater bubble oscillations
(NATO. SACLANTCEN, 1999/02)Pressure - time series from breathing mode oscillation of large (centimeter scale or larger) underwater bubbles reveal much higher decay rates than can be explained using viscous, thermal, or radiative mechanisms which ... -
Generic Oceanographic Array Technologies (GOATS)'98: bi-static seabed scattering measurements using autonomous underwater vehicles
(NATO. SACLANTCEN, 1998/10)The GOATS'98 experiment was performed May 5-29, 1998 in shallow water off Marciana Marina, on the island of Elba, Italy. The experiment addressed some of the fundamental issues associated with using the new Autonomous Ocean ... -
Resonance analysis of the acoustic response of a water-filled cylindrical shell
(NATO. SACLANTCEN, 1998/09)The resonance analysis approach developed for characterizing free-field air-filled cylindrical shells in terms of geometrical and mechanical pararneters is extended to fluid-filled shells either in the freefield or proud ...