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Now showing items 31-40 of 49
A relation between multipath group velocity, mode number, and ray cycle distance
(CMRE, 2014/01)
Weston's ray invariant or "characteristic time" in a range-dependent environment is exactly equivalent to the Wentzel-Kramers-Brillouin phase integral for ducted normal modes. By considering a ray element it is shown that ...
Localization of small surface vessels through acoustic data fusion of two tetrahedral arrays of hydrophones
(CMRE, 2014/01)
Detection and tracking of vessels is important in confined areas such as marine parks or harbors. Nowadays, the presence of ships can be accurately monitored either by radar or via AIS system, while small vessels, which ...
An approximate form of the Rayleigh reflection loss and its phase: application to reverberation calculation
(NURC, 2012/04)
A useful approximation to the Rayleigh reflection coefficient for two half-spaces composed of water over sediment is derived. This exhibits dependence on angle that may deviate considerably from linear in the interval ...
Efficient dense sonar surveys with an autonomous underwater vehicle
(CMRE, 2014/01)
An algorithm for the in situ adaptation of the survey route of an autonomous underwater vehicle (AUV) equipped with side-looking sonars was recently proposed. This algorithm immediately exploits the through-the-sensor data ...
Multi-view SAS image classification using deep learning
(CMRE, 2017/11)
A new approach is proposed for multi-view classification when sonar data is in the form of imagery and each object has been viewed an arbitrary number of times. An image-fusion technique is employed in conjunction with a ...
Counter piracy surveillance requirements for early detection, military rescue, or evasion
(NURC, 2012/06)
Best practice for protection against pirates includes coordination with the military forces operating in the area, constant watch against the approach of pirates, and measures to prevent or delay their boarding. The time ...
Optimum sampling designs for a glider-mooring observing network
(CMRE, 2014/01)
Ocean observing systems (OOSs) constituted by moorings and gliders are becoming relevant in oceanographic and climate studies. In these observing networks, the temporal variability is captured by mooring observations, while ...
Detection, tracking and fusion of multiple HFSW radars for ship traffic surveillance: experimental performance assessment
(CMRE, 2014/05)
Low-power HF surface-wave radars fit well the role of long-range early-warning tools in maritime situational awareness applications, by virtue of their over-the-horizon coverage capability and continuoustime mode of ...
AUV-enabled adaptive underwater surveying for optimal data collection
(NURC, 2012/04)
A new adaptive strategy for performing data collection with a sonar-equipped autonomous underwater vehicle (AUV) is proposed. The approach is general in the sense that it is applicable to a wide range of underwater tasks ...