Browsing Reprints by Subject "Acoustic propagation"

Now showing items 101-105 of 105

    • The wave equation in a medium with a time-dependent boundary 

      Fortuin, Leonard (NATO. SACLANTCEN, 1974/02)
      It is shown that the Helmholtz equation is not exactly correct for a medium with a time-dependent boundary. The equation can be used with very good approximation when the time-derivative of the surface elevation is much ...

    • Theoretical calculation of transmission loss in the ocean 

      Aubell, Arne (NATO. SACLANTCEN, 1971/12)
      The topic that is dealt with in this paper is a method for c omputation of acoustic transmission loss by sound propagation in the ocean. The method i s based on the ray theory which is used in connection with an acoustic ...

    • Time domain finite difference methods for range dependent Biot media 

      Stephen, Ralph (NATO. SACLANTCEN, 1997)
      The physics of sound propagation in saturated, porous (Biot) media differs from propagation in fluids and elastic/anelastic solids because of the existence of a second compressional wave, the "slow" wave. Many environments ...

    • Two dimensional internal-wave spectra 

      Bell, T. H.; Bergin, J. M.; Dugan, J. P.; Hamilton, Z. C. B.; Morris, W. D.; Okawa, B. S.; Rudd, E. E.; Witting, J. (NATO. SACLANTCEN, 1975/10)
      Although spatial fluctuations of the sound speed in the ocean have a variety of causes, internal waves are thought to produce most of the fluctuations over horizontal scales ranging from several tens of metres to several ...

    • Vertical porosity and velocity fluctuations in shallow-water surficial sediments and their use in modeling volume scattering 

      Briggs, Kevin B.; Percival, Donald B. (NATO. SACLANTCEN, 1997)
      Variability in sediment porosity and velocity creates volume scattering which is a parameter used in high-frequency scattering models. High-resolution vertical profiles of sediment porosity and compresstonal wave velocity ...