Browsing by Title
Now showing items 821-840 of 882
-
The SACLANTCEN sphincter corer assembly = Carottier a sphincter du SACLANTCEN: part 1: a wide-diameter corer with waterproof core-catcher: part 2: an electrical engineering system
(NATO. SACLANTCEN, 1965/03)A long, wide-diameter corer with a waterproof core-catcher is described in Part I. Its design is closer to theoretically ideal proportions than most oceanographic corers, and the cores it provides appear to be unmodified ... -
The sea surface as a random filter for underwater sound waves
(NATO. SACLANTCEN, 1974/06)In this dissertation the phenomenon of scattering and reflection of underwater sound waves from the sea surface is studied by considering the surface sound channel as a random, time-dependent filter. This filter can be ... -
The seamount as a noise barrier
(NATO. SACLANTCEN, 1982/06)When the path from a localized noise source is intercepted by a seamount the shielded noise consists of a diffracted component and, if the seamount is close to a sufficiently smooth ocean surface , a multiply-reflected ... -
The steady state of the step structure in the Tyrrhenian Sea
(NATO. SACLANTCEN, 1978/10)A deep step structure, in which mixed layers alternate with high gradient interfaces, is a characteristic feature of the Tyrrhenian Sea. Three oceanographic cruises (May 1972, May 1973 and October 1974), supported by the ... -
The Strait of Sicily in relation to the general circulation of the Mediterranean
(NATO. SACLANTCEN, 1972/09) -
The structure of fronts in the seasonal thermocline
(NATO. SACLANTCEN, 1972/09)Some years ago, when the first continuous profiling temperaturesalinity- depth probes came available it was discovered that tht thermocline had a layered structure. The thickness of these layers was a few metres and ... -
The sub-bottom structure of the Gulf of La Spezia
(NATO. SACLANTCEN, 1968/12)The sub-bottom structure of the Gulf of La Spezia, Italy, has been investigated by continuous seismic profiling and sediment coring. The seismic profiles were used to develop contour plots of sub-bottom layers, which were ... -
The temperature structure in the upper layers of the Ligurian Sea and its seasonal variations
(NATO. SACLANTCEN, 1962/05)Water temperature measurements in the Ligurian Sea down to depths of 150 meters and meteorological data connected with these measurements for the period July 1960 to October 1961 are presented in the form of graphs and ... -
The temperature structure in the upper layers of the Ligurian Sea and its seasonal variations: supplement to SACLANTCEN technical report no. 8
(NATO. SACLANTCEN, 1964/04)Water temperature measurements, down to depths of 150 meters, and metereological data connected with these measurements carried out in t 1e Ligurian Sea in May and November 1962, are presented in the form of graphs and ... -
The use of Love waves to determine the geoacoustic properties of marine sediments
(NATO. SACLANTCEN, 1986/06)The importance of the geoacoustic properties of marine sediments for low-frequency shallow water propagation is well established. Reliable compressional properties can be obtained from laboratory analysis of collected ... -
The wave equation in a medium with a time-dependent boundary
(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
(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 ... -
Theory of scattering and reflection of sound from the sea surface
(NATO. SACLANTCEN, 1975/10)Theoretical work on scattering and reflection of sound from the random timevarying rough sea surface is critically reviewed. It is shown that sound scattering from the sea surface may be treated as a purely acoustic boundary ... -
Through-the-sensor geoacoustic inversion along a towed horizontal line array: results from real data set in the Mediterranean sea
(NURC, 2007/12)The assessment of active sonar performances in shallow water strongly depends on the environmental conditions. Of most importance, bottom properties are known to strongly affect the forward acoustic propagation and ... -
Time dependence of infrasonic ambient seafloor noise on a continental shelf
(NATO. SACLANTCEN, 1986/06)SACLANTCEN is conducting a long term programme of ambient noise measurements that cover the frequency band from 1 to 100 Hz. A sea-bed sensor consisting of three seismometers and a hydrophone has been deployed close to the ... -
Time domain finite difference methods for range dependent Biot media
(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 ... -
Time series variability in fluctuating ocean waveguides
(NATO. SACLANTCEN, 1999/07)The variability of signals propagating through an uncertain sound speed structure is addressed. Signals are assumed to travel in a narrow band adiabatically in modes and to experience fluctuations in sound speed which are ... -
Time-evolution modelling of seafloor scatter: Part 1: Theory
(NATO. SACLANTCEN, 1997/04)A time-series model for acoustic seafloor backscattering is described. -
Time-evolution modelling of seafloor scatter: Part 2: experimental verification
(NATO. SACLANTCEN, 1997/04)A time-evolution model of seafloor scatter is numerically implemented and experimentally verified. The model is based on expressing analytically the elementary time-backscattered response of every seafloor surface and every ... -
Time-frequency representation of model based high frequency broad band scattering from a rough interface
(NATO. SACLANTCEN, 1997)A formulism for scattering a broad band high frequency pulse from a randomly rough surface of n penetrable oceanic sediment is developed and used to investiyate the ability of local cosine transform (LCT) rime-frequency ...