Browsing Reprints by Subject "Acoustic propagation"

Now showing items 61-80 of 105

    • Ocean-basin reverberation from large underwater explosions: part 1: source-level and propagation-loss modelling 

      Blatstein, Ira M. (NATO. SACLANTCEN, 1975/10)
      Predicting the reverberant returns from ocean basin reflectors requires describing acoustic source levels for large, conventional underwater explosions, defining the two way propagation loss and signal spreading from the ...

    • Ocean-bottom reflectivity (a point of view) 

      Santaniello, S. R.; DiNapoli, Frederick R. (NATO. SACLANTCEN, 1975/10)
      The analysis procedures for extracting bottom loss values from pulsed acoustic signals that have interacted with the ocean bottom do not inherently consider sub-bottom refraction and reflection of sound, which are important ...

    • Oceanic layered microstructure and fronts 

      Johannessen, Ola M. (NATO. SACLANTCEN, 1971/12)
      This talk is divided into two parts: one deals with oceanic microstructure, with particular attention to the so-called "layered microstructure"; the other part is concerned with oceanic fronts. As an example of the latter ...

    • Position and shape of the surface shadow zone 

      De Raigniac, Bernard (NATO. SACLANTCEN, 1971/12)
      From surface reverberation studies conducted by SACLANTCEN's Target Classification Group"C , it has been found necessary to know before any sea experiment the precise position of the first surface shadow zone. Since normal ...

    • Random temperature structure as a factor in long-range propagation 

      Del Balzo, Donald R.; Moseley, W. B. (NATO. SACLANTCEN, 1975/10)
      A statistical description of horizontal thermal microstructure in anosotropic turbulence is developed for application with an existing acoustic propagation theory. The model predicts a temperature power density spectrum ...

    • Range and depth estimation by line arrays in shallow water 

      Klemm, Richard (NATO. SACLANTCEN, 1982/01)
      In shallow water sound propagates in terms of normal modes. The interference between the modes can be utilized to estimate range and depth of an acoustic source in shallow water by applying high resolution power estimators ...

    • Range-dependent normal modes in underwater sound propagation 

      Graves, Ronald D.; Nagl, Anton; Uberall, Herbert M.; Haug, Anton J.; Zarur, George L. (NATO. SACLANTCEN, 1975/10)
      Normal mode theory is best suited for the case of stratified media. Range dependence of the medium properties and of its boundary may nevertheless be taken into account in the framework of an adiabatic approximation provided ...

    • Ray convergence in a flux-like propagation formulation 

      Harrison, Chris H. (CMRE, 2014/01)
      The energy flux formulation of waveguide propagation is closely related to the incoherent mode sum, and its simplicity has led to development of efficient computational algorithms for reverberation and target echo strength, ...

    • Ray tracing on a mini-computer 

      Thompson, Martin; Wijmans, Willem (NATO. SACLANTCEN, 1971/12)
      It would appear that most people engaged in solving problems in ray- tracing, use programs written for large computers . These machines commonly have large memory sizes, fast cycle times and large word length 0 This paper ...

    • Ray tracing on a mini-computer 

      Thompson, Martin; Wijmans, Willem (NATO. SACLANTCEN, 1972/05)
      It would appear that most people engaged in solving problems in ray- tracing, use programs written for large computers. These machines commonly have large memory si~es, fast cycle times and large word length . This paper ...

    • Rays and statistical diffraction theory 

      Clarke, Richard H. (NATO. SACLANTCEN, 1971/12)
      A method of extending ray tracing is proposed, such that mediumscale irregularities of a statistical nature are taken into account along with large-scale irregularities in refractive index of the medium.

    • Relative contribution of surface roughness and bottom attenuation to propagation loss in shallow water 

      Kuperman, William A.; Ingenito, Frank (NATO. SACLANTCEN, 1975/10)
      A simulation study has been performed to investigate the relative importance of the contributions of surface roughness and bottom attenuation to propagation loss under differing environmental conditionso The NRL normal ...

    • Review of numerical models in underwater acoustics including recently developed fast-field program 

      Jensen, Finn B.; Schmidt, Henrik (NATO. SACLANTCEN, 1984/12)
      Two papers given by SACLANTCEN personnel at the NATO Advanced Research Workshop on Hybrid Formulation of Wave Propagation and Scattering at Castel Gandolfo, Rome, Italy on 30 August to 3 September 1983 are published as a ...

    • Role of propagation in ambient noise 

      Ross, Donald (NATO. SACLANTCEN, 1982/06)
      To be useful for modern ASW systems design and analyses, descriptions of ambient noise fields must go beyond average omnidirectional spectra and include horizontal and vertical patterns, fluctuations with time, dependencies ...

    • Seismic and hydroacoustic sensing of infrasonic noise in coastal waters 

      Schmalfeldt, Bernd; Rauch, Dieter (NATO. SACLANTCEN, 1982/06)
      Three-component ocean-bottom seismometers with radio links have been deployed in coastal waters to investigate natural and man-made noise at extremely low frequencies. Seismograms from one or up to three sensor stations ...

    • Sensitivity of ray theory to input data 

      Reeves, J. L.; Solomon, L. P. (NATO. SACLANTCEN, 1971/12)
      Acoustic propagation problems which are solved using ray theory require certain input data. In particular, the source and receiver locations, sound-velocity field and bottom and surface conditions are required. Frequently, ...

    • Shallow water propagation incorporating both bubble plumes and sea-surface roughness 

      Norton, Guy V.; Novarini, Jorge C. (NATO. SACLANTCEN, 1997)
      The effect of including a range dependent bubble layer and a suitable sea surface spectrum in modeling shallow water propagation is analyzed. Propagation is simulated through a hrghly accurate model based on a modified PE ...

    • Shallow-water coherence of broadband signals 

      Badiey, Mohsen; Simmen, J.; Tang, X. (NATO. SACLANTCEN, 1997)
      The frequency-dependent spatial and temporal variabilities of sound propagation in coastal regions is investigated by ezperiment and numerical simulations. Experimental observations show that temporal coherence of the ...

    • Shallow-water sound transmission measurements taken on the New Jersey continental shelf 

      Carey, William M.; Doutt, James A.; Evans, Richard; Dillman, Lynne (NATO. SACLANTCEN, 1993/08)
      Calibrated acoustic measurements were made under calm sea state conditions on the New Jersey shelf near the AMCOR 6010 borehole, a surveyed area with known geophysical properties. The experiment was conducted in 73 m water ...

    • Some acoustic effects of internal macrostructure 

      Mellen, Robert H.; Browning, David G. (NATO. SACLANTCEN, 1975/10)
      Some recent experimental developments relating to internal oceanographic- acoustic interactions are reviewed. Besides amplitude and phase fluctuations, a major concern is scattering into shadow regions. Associated oceanographic ...