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Fillinger, L. (author), Nijhof, M.J.J. (author), de Jong, C.A.F. (author)A decade ago, TNO developed RASP (Rapid Acoustic Signature Prediction), a numerical model for the prediction of the target strength of immersed underwater objects. The model is based on Kirchhoff diffraction theory. It is currently being improved to model refraction, angle dependent reflection and transmission (possibly through anisotropic...conference paper 2014
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Dol, H.S. (author)The timely detection of small hazardous objects at the sea surface, such as drifting mines, is challenging for ship-mounted sensor systems, both for underwater sensor systems like sonar and above-water sensor systems like radar and electro-optics (lidar, infrared/visual cameras). This is due to the low target echo strength and radar/lidar cross...conference paper 2014
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Ainslie, M.A. (author), Dahl, P.H. (author), de Jong, C.A.F. (author), Laws, R.M. (author)Geometrical spreading laws are widely used in underwater acoustics because they provide - if chosen carefully - an accuracy that is sufficient for many applications (source characterisation, impact assessment, sound mapping, regulation) for negligible computation time. The simplest and most widely used form is that corresponding to spherical...conference paper 2014
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Huntera, A. (author), Fillingera, L. (author), Clarijs, M. (author)In December 2013, TNO made underwater measurements in Aruba to assess the feasibility of reef health monitoring using passive acoustics; this work was conducted in collaboration with Aruba Ports Authority, Aruba Marine Park, and Aruba Reef Care Foundation. Ambient noise recordings were made at various locations around the reef over a period of...conference paper 2014
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Sertlek, H.O. (author), Ainslie, M.A. (author)Accurate and fast estimation of propagation loss (PL) is needed for simulations of sonar or acoustic communication performance, and for environmental risk assessment. Accurate calculation of PL in range dependent and lossy waveguides can require computationally expensive wave theory techniques . In this work, a new propagation model is...conference paper 2014
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Fillinger, L. (author), Mantouka, A. (author), de Jong, C.A.F. (author), Gloza, I. (author), Sanchez, A. (author), Moya, E. (author), Schael, S. (author), Lennartsson, T. (author), Petit, G. (author), Fardal, R. (author), Hasenpflug, H. (author), Beckers, A.L.D. (author)SIRAMIS is a project coordinated by the European Defence Agency standing for Signature Response Analysis on Multi Influence Sensors. As most of the international trade is carried out through marine routes, it is important to evaluate the vulnerability of the merchant vessel fleet to sea mines in order to be able to limit the potential exposure...conference paper 2014
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Nijhoff, M.J.J. (author)Current methods of automatic target detection and classification using low- to mid- frequency sonar are based on correlating the measured Target In the Environment Response (TIER) of potential targets with the TIERs in a database of known objects. Obtaining experimental TIER measurements of proud, partially and fully buried objects to populate...conference paper 2014
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Sertlek, H.O. (author), Aarts, G. (author), Brasseur, S. (author), Slabbekoorn, H. (author), ten Cate, C. (author), von Benda-Beckmann, A.M. (author), Ainslie, M.A. (author)Regulations for protecting and preserving the marine environment (e.g. in the USA and EU) often require investigating the potential effect of anthropogenic sound on marine life. The origin of underwater sound can be natural as well as anthropogenic. To assess the potential importance of various types of sounds, we constructed sound maps for the...conference paper 2014
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Espana, A.L. (author), Nijhof, M.J.J. (author), Williams, K.L. (author), Plotnick, D.S. (author), Marston, P.L. (author)When attempting to detect and classify objects in an ocean environment, it has been shown that the surrounding environment, specifically the target’s deployment within that environment, greatly affects the measured acoustic response. While sea trials go a long ways towards extending the development of better classification systems, they are...conference paper 2014
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Duijster, A.J. (author), Hunter, A. (author), van Vossen, R. (author), Beckers, A.L.D. (author)Detection of unexploded ordnance is challenging in the underwater environment, particularly when object burial occurs. A capability to detect buried targets has been demonstrated previously using TNO’s MUD low frequency sediment-penetrating sonar and other similar sonars. However, the high clutter rates encountered in practice have the potential...conference paper 2014
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Fillinger, L. (author), Hunter, A.J. (author), Clarijs, M.C. (author)Since 2010, TNO has conducted a number of experiments on passive diver detection in Dutch waters. We have demonstrated detection, localization and tracking of divers wearing open circuit and closed circuit underwater breathing apparatus as well as boats. However, until now, we have not conducted any such experiments in warm waters. The...conference paper 2014
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Binnerts, B. (author), von Benda-Beckmann, A.M. (author), van Beek, P.J.G. (author)In the oil & gas industry there is a trend towards more subsea activities. To improve gas recovery from existing and new fields at greater depths, the produced gas will be compressed, processed and transported via subsea templates and underwater networks (pipelines, flexible risers, etc.). Besides the huge consequences for the subsea...conference paper 2014
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Colin, M.E.G.D. (author), Binnerts, B. (author), Ainslie, M.A. (author), Benda-Beckmann, A.M. (author), Booth, C. (author), Bouton, N. (author), Harris, C.M. (author), de Jong, C.A.F. (author), Sertlek, H.O. (author), Slabbekoorn, H.W. (author)There is an increasing concern that anthropogenic underwater noise may have a negative impact on marine life. Governmental authorities are introducing regulations to address this problem. The European Commission, for instance, has adopted the Marine Strategy Framework Directive requiring EU Member States to achieve or maintain Good Environmental...conference paper 2014
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Harrison, C.H. (author), Schippers, P. (author), Snellen, M. (author), Weterings, A. (author), TNO Defensie en Veiligheid (author)The angle and frequency dependent reflective properties of the seabed can be determined from beam-steered ambient noise measurements on a vertical array of hydrophones. From the up-to-down ratio the beam-smeared modulus square of the plane wave reflection coefficient is obtained. Geo-acoustic parameters can be inverted by matching the measured...conference paper 2005
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Blarzino, G. (author), Ainslie, M.A. (author), Boek, W. (author), Simons, D.G. (author), Snellen, M. (author), TNO Defensie en Veiligheid (author)The design of a bistatic short-range, shallow water reverberation model is presented, which aims to reproduce the reverberation measurements carried out by TNO, TUS, FFI and KDA in the Vestfjorden area (Norway), during the RUMBLE project. These were collected by using a Low Frequency Active Sonar (LFAS) source received on a towed horizontal...conference paper 2005
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Hansen, R.E. (author), Callow, H.J. (author), Saebo, T.O. (author), Groen, J. (author), Quesson, B.A.J. (author), Sabel, J.C. (author), TNO Defensie en Veiligheid (author)An acoustic simulator is vital for the development of sonar data processing. The most important features in the TNO 3D simulator SIMONA are detailed target response including shadow, reverberation modelling, sonar properties and multipath. The verification and development of SIMONA was realized alongside with a wide range of measurements in a...conference paper 2005
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Jenserud, T. (author), Plaisant, A. (author), Ainslie, M.A. (author), TNO Defensie en Veiligheid (author)This paper presents results obtained during the EUCLID project RTP 10.16 called “RUMBLE” carried out with contribution of several European organisations: TUS in France, TNO-FEL in the Netherlands, KDA, FFI and NGU in Norway. The objective was to assess the capability of an Active Low Frequency Sonar to estimate bottom parameters in shallow water...conference paper 2005
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Schippers, P. (author), TNO Defensie en Veiligheid (author)Since the late eighties the sonar performance model ALMOST of TNO Defence, Security and Safety is under development. For active detection performance first a point target with one Target Strength (TS) value dependent on aspect angle was used, based on measurements or other sources. Within the Torpedo Defence System Test Bed (TDSTB), developed at...conference paper 2005
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Ainslie, M.A. (author), Dybedal, J. (author), Lam, F.P.A. (author), Simons, D.G. (author), Snellen, M. (author), TNO Defensie en Veiligheid (author)The sensitivity of sound speed to temperature makes it possible to use an echo sounder as a thermometer, provided that the salinity and water depth are known with sufficient precision. Could ‘echothermometry’ – i.e., the use of an echo sounder, or a network of echo sounders, to measure temperature in this way – provide a viable alternative to...conference paper 2005
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Sabel, J.C. (author), Groen, J. (author), Quesson, B.A.J. (author), TNO Defensie en Veiligheid (author)The acoustic shadow of a target is a strong classification clue in naval mine hunting. A shadow of bottom targets appears at relatively short ranges (≤ about 200 m) in high resolution images from sidescan or synthetic aperture sonar (SAS), against a background of sea floor reverberation. In SAS however, definition of the shadow reduces with...conference paper 2005