Reprints: Recent submissions
Now showing items 221-240 of 548
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Automatic change detection for the monitoring of cluttered underwater areas
(NURC, 2008/09)Automating the surveillance of cluttered underwater areas (such as ports) poses several problems, the main one being the high number of contacts that any automatic target recognition (ATR) system will produce when surveying ... -
Security versus defence: dual use from a system requirement perspective
(NURC, 2008/09)The developers of defence technologies in both industry and national laboratories carried their culture for military system development into the evolving security mission, even for systems that are to be used by civilian ... -
Regional reflection seismic exploration of the Strait of Sicily
(NATO. SACLANTCEN, 1972/09)A regional seismic reflection survey was performed by OGS in 1970 on the Sicily Channel, using multichannel digital techniques and flexotir source. Reflections up to about 5 s (two-way time) have been obtained. The analysis ... -
A comparative analysis of side-looking sonars for rapid classification of underwater intruders
(NURC, 2008/09)One aspect of NURC's 2008 efforts in port protection involves building a prototype system for countering a subsurface threat. Such a capability against underwater intruders in ports requires surveillance of the underwater ... -
Tank measurements of scattering from a resin-filled fibreglass spherical shell with internal flaws
(NURC, 2008/09)This paper presents results of acoustic inversion and structural health monitoring achieved by means of low to midfrequency elastic scattering analysis of simple, curved objects, insonified in a water tank. Acoustic elastic ... -
Review of target strength information for waterside security applications
(NURC, 2008)Estimates of the target strength of objects, such as for example scuba tanks and swimmer delivery vehicles, are parameters of interest in all phases of the design of waterside security systems. Results of numerical target ... -
Heterogeneous underwater networks for ASW: technology and techniques
(NURC, 2008/06)NATO's research and technology objectives for anti-submarine warfare (ASW) include persistent scalable heterogeneous wide-area surveillance networks for the littoral environment. Network and system design considerations ... -
Geoacoustic inversion using multipath pulse shape
(NURC, 2008/09)Experimental data, measured in a shallow water region of the Mediterranean Sea, are used to show that the variation of received intensity with time is well described by existing expressions [Harrison and Nielsen, J. Acoust. ... -
Target detection and location with ambient noise
(NURC, 2008/09)By placing a vertical array in an ambient noise field and forming an upward and a downward beam one obtains two time series which can be cross correlated to reveal a subbottom profile of the seabed [Siderius et al., J. ... -
At-sea measurements of acoustic elastic scattering by a 1.5m-long cylinder made of composite materials
(NURC, 2007/12)Monostatic and bistatic acoustic scattering measurements were performed on solid-filled fibreglass objects (a sphere and a cylinder with hemispherical endcaps) deployed proud on a sandy seabed and insonified by a rail-mounted ... -
Tank measurements of elastic scattering by a resin-filled fiberglass spherical shell
(NURC, 2007/12)Acoustic elastic scattering measurements were conducted in a tank on a 6cm radius fibreglass spherical shell filled with a low-shear-speed epoxy resin. Preliminary measurements were conducted also on the void shell before ... -
Through-the-sensor geoacoustic inversion along a towed horizontal line array: results from real data set in the Mediterranean sea
(NURC, 2007/12)The assessment of active sonar performances in shallow water strongly depends on the environmental conditions. Of most importance, bottom properties are known to strongly affect the forward acoustic propagation and ... -
Bathymetry, gravity and magnetism in the Strait of Sicily
(NATO. SACLANTCEN, 1972/09)In cooperation with SACLANTCEN, O.G.S. started in 1961 the geophysical survey of the Mediterranean Sea (Allan, Morelli, 1971 ), which after 1966 was continued in the seas around Italy on the oceanographic ships of C.N.R. ... -
Separability of scattering and reflection parameters in reverberation inversion
(NURC, 2007/11)A premise of reverberation inversion is that one can separate geoacoustic reflection properties from scattering properties since their effects on reverberation are distinguishable. Some doubt has been cast on this premise ... -
On the integration of through-the-sensor geoacoustic inversion techniques for environmental adaptation schemes in low frequency active sonars
(NURC, 2007/12)The environmental conditions in shallow water areas are known to strongly affect the performances of low frequency active sonars (LFAS). In particular, interactions of the acoustical field with the seabed interface have ... -
Multipath pulse shape in a refracting environment
(NURC, 2007/11)Multiple boundary interactions in shallow water propagation introduce a more or less Gaussian angle distribution at a distant receiver. When all paths are added the result is 'mode-stripping', i.e. the steep rays are ... -
Network-enabled information fusion in support of underwater research
(NURC, 2007/11)Advanced communication and information processing techniques can be applied to underwater research to enable new ways of enhancing real-time experimental outcome. This paper is concerned with three main areas where ... -
Experimental results of 300 kHz shallow water synthetic aperture sonar
(NURC, 2007/11)The design of a shallow water synthetic aperture sonar (SAS) requires an understanding of key system and environmental issues. The main factors which limit SAS performance are micronavigation accuracy, where micronavigation ... -
Adaptive sub-band processing in active detection and tracking
(NURC, 2007/11)Broadband active systems have the potential to increase detection performance in reverberation-limited areas through increased signal bandwidth, i.e. small resolution cell. However, large bandwidth could over-resolve the ... -
Multistatic sonar: a road to a maritime network enabled capability
(NURC, 2007/10)NATO's operational requirements emphasize interoperability of platforms participating in coalition task forces. Intelligently fusing data of multiple sensor systems and the development of adapted tactics are necessary steps ...