Browsing by Title
Now showing items 396-415 of 882
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Identification of sea surface temperature (SST) variability areas through a statistical approach using remote sensing and numerical ocean model data
(CMRE, 2019/06)An understanding of environmental variability (stability/instability) is important to support operational planning of expeditionary warfare and littoral operations, as well as for preparing the Recognized Environmental ... -
The impact of covariance localization on the performance of an ocean EnKF system assimilating glider data in the Ligurian Sea
(CMRE, 2019/05)Data assimilation through an ensemble Kalman filter (EnKF) is not exempt from deficiencies, including the generation of long-range unphysical correlations that degrade its performance. The covariance localization technique ... -
The impact of sea state on HF surface-wave radar ship detection and tracking performances
(CMRE, 2019/06)Nowadays, we face an ever increasing interest in new technologies and solutions for the maritime surveillance (MS) domain. In such a context, oceanographic high-frequency surface-wave (HFSW) radars have started to get ... -
Impact of seafloor and water column parameter variations on signal-to-background ratio estimates: a sensitivity study based on sonar performance modeling
(NURC, 2006/08)Regardless of how accurate modeling can be, if the set of assumptions made with regard to the propagation conditions are not precise, sonar performance predictions diverge from the corresponding measured values. Here a ... -
Impact of uncertain environmental knowledge on the shallow-water transfer function
(NATO. SACLANTCEN, 1992/12)It is assumed that the acoustic channel can be modeled as a linear time-invariant space-variant filter. In this case, from linear systems theory, it is known that the filter output, that is the predicted source signal ... -
Improvements to data networks in support of REA during Generic Oceanographic Array Technology (GOATS) 98
(NATO. SACLANTCEN, 2000/05) -
Impulse response of a layered bottom
(NATO. SACLANTCEN, 1967/01)Numerical methods are used for the Fourier inversion of the frequency-dependent loss transfer function. Because of the non-zero finite values of the integrand for an infinite high frequency, the asymptotic value is subtracted ... -
In-situ acoustic received level measurements with glider based reactive behaviour
(CMRE, 2019/06)Buoyancy-driven underwater gliders are typically employed to sample the water column environment in the ocean [1]. As one of the efforts of extending the capabilities of traditional underwater gliders, CMRE has been working ... -
Incidence du bruit acoustique de thoniers ligneurs et senneurs français sur leurs performances de peche
(NATO. SACLANTCEN, 1985/01)Les auteurs présentents quelques expertises acoustiques provenant de deux études réalisées par le GERBAM: - la première, sur 95 thoniers ligneurs pratiquant la pêche du germon (Thunnus alalunga), -la second, sur 18 thoniers ... -
Incoherent sub-band averaging for improved target detection and Doppler estimation in linearly frequency modulated continuous active sonar
(CMRE, 2019/05)Linear frequency modulated (LFM) continuous active sonar (CAS) waveforms show promise for use in target tracking given that waveforms can be split into sub-waveforms (sub-bands), thereby increasing the target refresh rate. ... -
Increasing the operational safety of autonomous underwater vehicles using the JANUS communication standard
(CMRE, 2019/05)Increasing the operational safety of Autonomous Underwater Vehicles (AUVs) is necessary to fully explore their potential. Currently, AUV operations are limited by several constrains including the need to guarantee no ... -
Influence of background-noise spatial coherence on high-resolution passive method
(NATO. SACLANTCEN, 1982/06)New signal processing methods for passive listening have appeared recently : they are called "high resolution" methods because they have theoretically a better resolving power than conventional or adaptive beamforming . ... -
Influence of internal waves on sound propagation in the SOFAR channel
(NATO. SACLANTCEN, 1975/10)In this paper theoretical investigations due to the influence of internal waves to sound propagation in the SOFAR-channel are presented. The undisturbed acoustic field is described by a normal-mode model. The disturbance ... -
Information and source quality ontology in support of maritime situational awareness
(CMRE, 2019/05)To support situation awareness, the benefit of using a variety of sources is undeniable although it brings additional challenges related to possible conflicting information, heterogeneity in data formats, semantics, ... -
Infrared detection of marine mammals
(NURC, 2005/12)An infrared (IR) binocular, designed for in-the-field military applications, was tested using in situ marine mammals during the Mar Ligure Joint Experiment 2003 (MLJX03) that took place in August-September 2003 onboard the ... -
Instrumentation for crosshole geoacoustic measurements in unconsolidated sediments
(NATO. SACLANTCEN, 1994/06)Research tools are described that enable direct measurements of sediment properties as a function of depth in unconsolidat,ed sediments. The first tool is a hole making device that sits on the sea floor and utilizes pneumatic ... -
Intensity and phase fluctuations in low-frequency acoustic transmission through internal waves
(NATO. SACLANTCEN, 1975/10) -
Intensity at caustics
(NATO. SACLANTCEN, 1971/12)The classical divergence expressions predict an infinite intensity at caustics. This infinite intensity is a fundamental limitation of geometrical acoustics (ray theory). The intensity at a caustic is of primary concern ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1974/02)A method is presented for the calculation of sound intensity using only one ray. The sound-velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ... -
Intensity calculations along a single ray
(NATO. SACLANTCEN, 1971/12)A method is presented for the calculation of sound intensity using only one ray. The sound velocity profile is assumed to be continuous up to the second derivative and it is supposed that the ray equations are solved ...