Browsing by Title

Now showing items 81-100 of 882

    • Acoustic characterization of a shallow water site 

      Cable, P.; Marshall, W.; Kooij, Theo; Skarda, G.; Waldman, K. (NATO. SACLANTCEN, 1993/08)
      Results are presented from an exercise aimed at providing a low frequency active sonar environmental characterization of a specific shallow water site in the Gulf of Mexico. Downward refracting acoustic transmission and ...

    • Acoustic characterization of submerged aquatic vegetation 

      McCarthy, Elena (NATO. SACLANTCEN, 1997)
      The acoustic characteristics of submerged aquatic vegetation (SAV) were investigated in order to enhance the performance of mine-hunting and weapon sonars in littoral reglons. The specres of seagrass initially studied was ...

    • Acoustic effects of internal microstructure 

      Mintzer, David (NATO. SACLANTCEN, 1975/10)

    • Acoustic impact of upper ocean models 

      Porter, M. B.; Piacsek, Steve; Henderson, Laurel; Jensen, Finn B. (NATO. SACLANTCEN, 1989/12)
      The upper mixed-surface layer of the ocean, with its homogeneous vertical temperature profile, provides a somewhat special acoustic propagation environment where the sound speed will increase (due to pressure) down to the ...

    • Acoustic models at SACLANTCEN 

      Schneider, Hans G. (NATO. SACLANTCEN, 1995/03)
      The Environmental Modelling Group at SACLANTCEN maintains a suite of computer codes to model sound propagation in the ocean. This suite contains numerical models to cover all environmental conditions and acoustic frequencies ...

    • 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 ...

    • Acoustic propagation models as viewed by the sonar systems designer 

      Reeves, J. L. (NATO. SACLANTCEN, 1971/12)
      The purpose of this paper is to consider the efforts performed in the development of ray acoustic propagation analyses from the viewpoint of advanced sonar system design. In particular, those parameters required of such ...

    • Acoustic propagation through oceanic fronts 

      Daintith, Maurice J. (NATO. SACLANTCEN, 1971/12)
      A resume was given of recent experiments in the Mediterranean, East of Malta, designed as a preliminary test of the effect of oceanic fronts on acoustic propagation. It was apparent that in certain circumstances the ...

    • Acoustic properties of the sea floor: a review 

      Hamilton, Edwin L. (NATO. SACLANTCEN, 1975/10)

    • Acoustic scattering from rough surfaces 

      Hurdle, B.; Flowers, K. D.; DeSanto, John Anthony (NATO. SACLANTCEN, 1975/10)
      A review of scattering from the ocean bottom and ocean ice cover is given. Areas of deficiency are cited.

    • Acoustic scintillations of acoustic waves 

      Munk, B. (NATO. SACLANTCEN, 1975/10)

    • Acoustic signal dispersion and distortion by shallow undersea transmission channels 

      Rice, Joseph A. (NATO. SACLANTCEN, 1997)
      The undersea littoral is an adverse medium for acoustic signal transmission to horizontal ranges of many water depths. Reflections and scattering in the bounded, nonhomogeneous channel disperse the arrivaj of received ...

    • Acoustic source characteristics of merchant ships 

      Heine, John C. (NATO. SACLANTCEN, 1982/06)
      Merchant ships are sources of broadband acoustic noise which can interfere with and confuse ocean surveillance. The purpose of this discussion is to review: the status of research on and measurements of merchant ship ...

    • Acoustic source-level measurements for a variety of merchant ships 

      Scrimger, Paul; Heitmeyer, Richard M. (NATO. SACLANTCEN, 1988/07)
      This report describes a set of 50 source spectra obtained from merchant ships of opportunity near Genova, Italy. These spectra were obtained from radiated-noise spectra measured on a towed array and a transmission-loss ...

    • Acoustical characteristics of the sea floor: experimental techniques and some examples from the Mediterranean Sea 

      Akal, Tuncay (NATO. SACLANTCEN, 1974/11)
      The acoustical properties of the sea floor are primarily determined by the physical properties of the sediments, layering in the sediments, and the roughness of the bottom and sub-bottom. Over the last decade many cores ...

    • 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 ...

    • Acquisition and processing of oceanographic data by a sea-going computer: an oceanographic tool and a complementary facility for acoustic trials 

      Spina, Francesco (NATO. SACLANTCEN, 1972/05)

    • Active contours for synthetic aperture sonar snippet registration 

      Dugelay, Samantha; Fox, Warren L. J. (CMRE, 2019/06)
      In mine-hunting operations, there is currently a strong focus on using autonomous systems in order to remove personnel and ships from the minefield. These systems must perform their missions effectively, and the collected ...

    • Active detection enhancement in coastal areas 

      Haralabus, Georgios; Baldacci, Alberto; Laterveer, Rene (NURC, 2006/08)
      The processing chain used for active detection analysis in association with measures of performance that allow real time performance monitoring is presented. Real life examples demonstrating environmental volatility ...

    • Active signal detection in shallow water using the Page test 

      Abraham, Douglas A.; Willett, Peter K. (NATO. SACLANTCEN, 1996/11)
      The use of active sonar in shallow water results in received echoes that may be considerably spread in time compared to the transmitted wave form. The duration and structure of the spreading and the time of occurrence of ...