Now showing items 161-180 of 548

    • Gas bubbles in the sea: a review and model proposals 

      Williams, Robert Bruce; Foster, Leslie A. (NATO. SACLANTCEN, 1975/10)
      The literature pertaining to both free bubbles (pt 1) and bubbles associated with fish anotomy (pt 2) is reviewed with particular emphasis on their distributions in the sea and influencing factors. An attempt is made to ...
    • Acoustical probing for microbubbles at sea 

      Medwin, Herman (NATO. SACLANTCEN, 1975/10)
      Free gas bubbles have been indicted for many physical processes at sea including: scavenging detritus and chemicals from the ocean volume; generating droplets whose salts affect thunderstorm activity over the sea; providing ...
    • Separation of measured noise coherence matrix into Toeplitz and Hankel parts 

      Harrison, Chris H. (CMRE, 2017/08)
      The cross-spectral density of ocean ambient noise is usually estimated from the product of the complex hydrophone signals, each of which already corresponds to the summed responses of sources from all angles. The true ...
    • Noise sources in the ocean - part 2 

      Daintith, Maurice J. (NATO. SACLANTCEN, 1975/10)
      Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ...
    • Acoustic noise models 

      Cox, Henry (NATO. SACLANTCEN, 1975/10)
      The question of modeling the vertical directionality of ambient noise in the ocean is considered. The problem of converting from a description in terms of directional density function to a description in terms of the ...
    • Fostering the use of JANUS in operationally-relevant underwater applications 

      Petroccia, Roberto; Alves, João; Zappa, Giovanni (CMRE, 2017/11)
      This paper presents the use of JANUS in operationally-relevant underwater applications. JANUS is an open, simple and robust digital coding technology currently in process to become a NATO standard. Two underwater scenarios ...
    • Noise sources in the ocean - part 1 

      Wille, Peter C. (NATO. SACLANTCEN, 1975/10)
      Following a brief historical survey of the development of our knowledge of the origins and characteristics of ambient noise in the ocean, the principal known sources of noise are described. These are: environmental origin, ...
    • Automated port traffic statistics: from raw data to visualization 

      Cazzanti, Luca; Davoli, Antonio; Millefiori, Leonardo (CMRE, 2017/11)
      We describe how we leveraged best practices in big data processing pipeline design and visual analytics to prototype the Maritime Patterns-of-Life Information Service (MPoLIS), an information product currently under ...
    • A distributed ID assignment and topology discovery protocol for underwater acoustic networks 

      Petroccia, Roberto (CMRE, 2017/11)
      This paper presents a new protocol to self assign node IDs in an Underwater Acoustic Network (UAN). The proposed solution, termed DIVE for Distributed Id assignment and topology discoVEry, is fully distributed and ...
    • Decision tree-based adaptive modulation for underwater acoustic communications 

      Pelekanakis, Konstantinos; Cazzanti, Luca; Zappa, Giovanni; Alves, João (CMRE, 2017/11)
      Underwater acoustic channels are characterised by non-stationary fading statistics and consequently, a modulation scheme optimally designed for a specific fading model will underperform when the channel statistics ...
    • Supporting AUV localisation through next generation underwater acoustic networks: results from the field 

      Munafó, Andrea; Furfaro, Thomas C.; Ferri, Gabriele; Alves, João (CMRE, 2017/11)
      This work describes how the localisation of autonomous underwater vehicles can be supported through net-worked acoustic communication. The localisation approach in-cludes timing information within acoustic messages to ...
    • Adaptive underwater sonar surveys in the presence of strong currents 

      Williams, David P.; Baralli, Francesco; Micheli, Michele; Vasoli, Simone (CMRE, 2017/11)
      We consider the task of conducting underwater surveys with a sonar-equipped autonomous underwater vehicle (AUV) in environments with strong currents. More specifically, this topic is addressed in the context of mine ...
    • A data-driven control strategy in synergy with continuous active sonar for littoral underwater surveillance 

      Ferri, Gabriele; Munafó, Andrea; Alves, João; LePage, Kevin D. (CMRE, 2017/11)
      In this work, we describe a data-driven Mission Management Layer (MML) running on-board AUVs which manages the phases of a littoral surveillance mission and exploits the characteristics of Continuous Active Sonar (CAS) ...
    • Multi-view SAS image classification using deep learning 

      Williams, David P.; Dugelay, Samantha (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 ...
    • Distributed information fusion in multistatic sensor networks for underwater surveillance 

      Braca, Paolo; Goldhahn, Ryan A.; Ferri, Gabriele; LePage, Kevin D. (CMRE, 2017/11)
      Surveillance in antisubmarine warfare has traditionally been carried out by means of submarines or frigates with towed arrays. These techniques are manpower intensive. Alternative approaches have recently been suggested ...
    • Moving JANUS forward: a look into the future of underwater communications interoperability 

      Alves, João; Furfaro, Thomas C.; LePage, Kevin D.; Pelekanakis, Konstantinos; Petroccia, Roberto; Zappa, Giovanni (CMRE, 2017/11)
      In the past 8 years, the Centre for Maritime Research and Experimentation (CMRE) has developed, tested and promoted JANUS - a robust and simple modulation and coding scheme to be used as the first standard to support ...
    • JANUS-based services for operationally relevant underwater applications 

      Petroccia, Roberto; Alves, João; Zappa, Giovanni (CMRE, 2017/11)
      This paper presents the design, test, and experimentation at sea of four JANUS-based services for operationally relevant underwater applications: 1) first contact and language switching; 2) transmission of automatic ...
    • Joint probabilistic data association tracker for extended target tracking applied to X-band marine radar data 

      Vivone, Gemine; Braca, Paolo (CMRE, 2017/11)
      X-band marine radar systems are flexible and low-cost tools for monitoring multiple targets in a surveillance area. Although they may suffer from several sources of interference, e.g., sea clutter, they can provide ...
    • Maritime surveillance using multiple high-frequency surface-wave radars 

      Maresca, Salvatore; Braca, Paolo; Horstmann, Jochen; Grasso, Raffaele (CMRE, 2014/05)
      In the last decades, great interest has been directed toward low-power high-frequency (HF) surface-wave radars as long-range early warning tools in maritime-situational-awareness applications. These sensors, developed for ...
    • Underwater acoustics - modelling: keynote address 

      Pryce, Aubrey W. (NATO. SACLANTCEN, 1975/10)