Browsing CMRE Publications by Title
Now showing items 829-848 of 882
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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 ... -
Toeplitz constrained adaptive beamforming with auxiliary data
(NATO. SACLANTCEN, 1997/02)Submarine and mine detection using active sonar face similar problems when adaptive beamforming is required to provide high angular resolution or to suppress angularly isolated interferences. Both -
Toward the development of secure underwater acoustic networks
(CMRE, 2019/05)Underwater acoustic networks (UANs) have been recognized as an enabling technology for various applications in the maritime domain. The wireless nature of the acoustic medium makes UANs vulnerable to various malicious ... -
Towards fully autonomous underwater vehicles in ASW scenarios: an adaptive data driven AUV mission management layer
(CMRE, 2019/06)We present an adaptive, data driven Mission Management Layer (MML) to manage the phases (surveillance, track prosecution and target reacquisition) of the mission of AUVs operating as receiver nodes in a multistatic network ... -
Tracking an unknown number of targets using multiple sensors: a belief propagation method
(CMRE, 2019/06)We propose a multisensor method for tracking an unknown number of targets. Low computational complexity and very good scalability in the number of targets, number of sensors, and number of measurements per sensor are ... -
Transmission-loss characteristics and geoacoustic model for an outer Albanian continental shelf platform in the south-east Adriatic sea
(NATO. SACLANTCEN, 1996/03)Transmission-loss experiments have been canied out on the outer Albanian Shelf. The acoustic measurements were performed together with a combined oceanographic and geological-geophysical survey which identified the different ... -
Transmission-time variability, vertical spatial and temporal analysis of NAPOLI'85, an experiment in the Tyrrhenian Sea
(NATO. SACLANTCEN, 1989/09)An acoustic propagation experiment (NAPOLI '85) was carried out in the Tyrrhenian Sea in October 1985 in which signals from a broadband source were recorded at a range of 5 km with a vertical 62-m hydrophone array over a ... -
Twenty years of research at the SACLANT ASW Research Centre: 1959-1979
(NATO. SACLANTCEN, 1980/01) -
Two dimensional internal-wave spectra
(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 ...