CMRE Open Library: Recent submissions
Now showing items 361-380 of 882
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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 ... -
Oceanographic conditions in the Antalya Basin in water
(NATO. SACLANTCEN, 1998/07)From an oceanographic survey of the Antalya Basin in February 1997 the following horizontal circulation pattern was found: The Asia Minor Current (AMC) was detached from the Turkish coast flowing to the southwest between ... -
Yellow Shark Spring '95: inversion results from sparse broadband acoustic measurements over a highly range dependent soft clay layer
(NATO. SACLANTCEN, 1998/06)In May 1995, SACLANTCEN performed broad-band (200-800 Hz) acoustic measurements in the Giglio basin off the coast of Italy as part of the Yellow Shark inversion experiments. In this paper, inversion of sparse, broad-band ... -
Numerical simulation of the effects of bathymetry on underwater sound propagation using three-dimensional parabolic models
(NATO. SACLANTCEN, 1998/03)Two different three-dimensional parabolic equation (PE) methods are -
Detection of buried objects in the seabed: a simple model study
(NATO. SACLANTCEN, 1998/10)The problem of detecting an object buried in the seabed is studied by means of a simple model. In this model, the object is a rigid sphere buried in a bottom modelled as a fluid half space. The scattered field is determined ... -
Remote sensing of topographically-induced upwelling in the southern coastal region of Sicily
(NATO. SACLANTCEN, 1998/09)Upwelling signatures caused by variations in bottom topography along the southeastern Sicilian coast are identified, using spaceborne remote sensing Advanced Very High Resolution Radiometer (AVHRR) imagery, ERS-1 and ... -
A summary of oceanographic data obtained in deep water in the Strait of Sicily in May 1970: MILOCMED surv 70
(NATO. SACLANTCEN, 1972/09)Observations of temperature and salinity using a TSD profiling system were made down to 500 m in a deep water area southeast of Pantelleria Island in the Strait of Sicily in May, 1970. The usual two layer system was observed, ... -
Detection of buried objects at low grazing angles: preliminary experimental results
(NATO. SACLANTCEN, 1998/06)This report considers the acoustic detection of objects buried in the seabed, and especially the possibility of using subcritical insonification geometries in order to increase coverage rate. -
Physics of 3-D scattering from rippled seabeds and buried targets in shallow water
(NATO. SACLANTCEN, 1998/05)The new OASES-3D code developed at MIT is used to investigate the spatial and temporal characteristics of reverberation from rippled seabeds insonified by narrow beam sonars such as the TOPAS parametric source. It is shown ... -
Experimental demonstration of the focused acoustic field in the ocean
(NATO. SACLANTCEN, 1998/10)An experiment conducted in the Mediterranean Sea in April1996 demonstrated that a time reversal mirror (or phase conjugate array) can be implemented to spatially and temporally refocus an incident acoustic field back to ... -
Mechanisms for subcritical penetration into a sandy bottom: experimental and modelling results
(NATO. SACLANTCEN, 1998/05)This paper presents the results of a recent study whose overall objectives are to determine the mechanism(s) contributing to subcritical acoustic penetration into ocean sediments, and to quantify the results for use in ... -
Oceanographic measurements of the West Black Sea: November 26 to December 14, 1995
(NATO. SACLANTCEN, 1998/06)Mediterranean water inflow into the Black Sea is investigated using acoustic and oceanographic data obtained in the Black Sea exit region. Temporal and spatial variability in the flow and their relation to atmospheric and ... -
Penetration of acoustic waves into sandy seafloors at low grazing angles: the Helmholtz-Kirchhoff approach
(NATO. SACLANTCEN, 1998/08)The Helmholtz-Kirchhoff integral is applied to model the penetration of sound waves into sandy seafloors at grazing angles above and below the critical angle. Although the conditions for the validity -
Probability of false alarm estimation in oversampled active sonar systems
(NATO. SACLANTCEN, 1998/08)The probability of false alarm (Pfa)in active sonar systems is an -
Modelling acousto-elastic waveguide/object scattering with the Rayleigh hypothesis
(NATO. SACLANTCEN, 1998/06)In this memorandum the plane wave scattering matrices for a range-dependent seabed and upper free surface are computed using the -
A study of the turbulent flow and character of the water masses over the Sicilian ridge in both summer and winter
(NATO. SACLANTCEN, 1972/09)The western sill region of the Strait of Sicily lies between Sicily (Capo Lilibeo) and Tunisia (Cap Bon) and is part of the submarine ridge separating the eastern from the western Mediterranean. [Fig. lJ. It was studied ... -
Modelling of scattering by partially buried elastic cylinders
(NATO. SACLANTCEN, 1998/02)The work of a previous memorandum on the modelling of scattering by a partially buried cylinder is extended to allow the cylinder to have full elasticity (and not just be a fluid structure as in the previous work). The ...