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Passive sound speed estimation using radiated ship noise is an appealing approach for long-term ocean observation close to ship lanes. In this paper we analyze the noise recorded in two drifting vertical line arrays (VLAs) deployed 1 km apart, in Setúbal's underwater canyon area off the west coast of Portugal during the RADAR'07 sea trial. Automatic Information System (AIS) recordings for this period...
In this paper experimental tests on a small scale tubular linear generator to be applied to wave rollers device are presented. A reduced scale of gnerator is presented and experimental results obtained in on test bench are shown. Experimental waveforms of current and voltage are recorded. Simulation results are compared to the experimental ones in order to validate the mathematical models used.
This paper describes an underwater mobile target localization and tracking by using an autonomous surface vehicle for which the successive ranges between the target and the reference are the only information. In a dynamic system, such as range-only single-beacon underwater target tracking, a state-space model can be characterized, where the state vector may include position, and velocity of the mobile...
In passive acoustic monitoring, source localization using multipath propagation can be challenging whenever the source-receiver configuration leads to overlapping multipath arrival patterns. We propose a single-hydrophone model-based method with matched-impulse response (IR) processing that exploits unresolved multipath arrival patterns to locate the source in 3D, making the best use of the bathymetric...
This paper presents an innovative system able to convert a variable bidirectional linear motion into a unidirectional rotary motion. The device could be a successful solution in sea wave application.
This article covers research into rotational speed control for oscillating water column converters (OWC). The primary focus is the improvement of the Wells turbine performance by controlling its rotational speed. In this sense, the proposed control scheme has been implemented based on the NEREIDA MOWC demonstration project, a breakwater wave plant located in the Basque location of Mutriku, using Wells...
Underwater images suffer from poor visibility due to color casts and light scattering that caused by physical properties existing in underwater environments. Degraded underwater images lead to a low accuracy rate of underwater object detection and recognition. To solve this problem, a novel underwater image enhancement method which combines adaptive color correction and image dehazing based on atmospheric...
Realistic descriptions of vertical sound speed profiles are essential for modelling underwater acoustic fields. Errors in the vertical sound speed profile will have negative impact on the acoustic propagation modelling. Ocean models provides vertical profiles of temperature and salinity, from which sound speed can be derived, covering large areas with high spatiotemporal resolution. Previous experience...
The paper presents a practical Doppler estimator to be used in underwater acoustic (UWA) channels. The estimation is performed using OFDM pilot signals. The OFDM pilot signals are passed through a Doppler channel that adds the above effects to the signal. The receiver then performs Doppler estimation on the signal. The estimator finds an estimate for the Doppler scaling factor (also called the mach...
The proposed paper introduces a novel method for range estimation of acoustic sources, both cetaceans and industrial sources, in deep sea environments using supervised learning with neural networks in the contex of a single sensor, a compact array, or a small aperture towed array. The presented results have potential both for industrial impact and for the conservation and density estimation of cetaceans...
The effect of variable-length towed cable on the motion of the secondary towed vehicle should be taken into consideration during its deployment. In order to predict the motion state of the secondary towed vehicle during deploying stage and obtain the position of it and the configuration of towed cable precisely and timely, an upgraded Lagrangian method is adopted. The movement of towed cable's particles...
In Bayesian inversion schemes, geoacoustic parameter values and associated uncertainties normally are obtained through sampling approaches, e.g., Metropolis-Hastings (M-H) sampling. This paper presents an attempt to solve this problem through applying a particle filter (PF) to solitary data input as collected in the Yellow Sea, China, 2002. In the experiment, a 38-g explosive charge was used as a...
Underwater images often suffer from color and contrast degradation, because the light is absorbed and scattered while traveling in water. Although the physical process of the underwater images seems similar to the outdoor haze images, conventional dehazing methods fail to generate accurate results since colors associated to different wavelengths have different attenuation rates in underwater conditions...
This paper proposes a practical system of the fish size measurement which is effective and simple. Because the fry we measured is very small, the main technical problem when we measure the fish size is to measure accurately without hurting them. Although the live fish can be measured directly or after anesthesia, the fry will be damaged. So we present the system of fish size measurement without any...
To adopt the wave condition of the East China Sea, a new kind of the overtopping wave power device has been designed, and it has a multi-level ramp to capture more wave energy. According to the experimental statistics and the simulation data, the parameters of the structure were confirmed. Then, the simulation experiment was carried out through the Computational Fluid Dynamics (CFD) software. The...
We focus on the segmentation of sonar images for the aim of underwater object detection. Speckle noise and intensity inhomogeneity may cause false detections, and complex seabed textures like sand-ripples and sea-grass often lead to false segmentation. To tackle these problems, we propose a new method to incorporate the possible spatial correlation between neighboring pixels in the sonar image for...
In 1998, JAMSTEC started the development project of the first prototype of a long-range cruising AUV (LCAUV) to evaluate fundamental technologies needed to travel through under the ice covered area of the Arctic. In 2005, The LCAUV, Urashima, achieved 317 km continuous cruising powered by a deep sea fuel cell developed in JAMSTEC [1]. We then moved to next stage and have conducted to design the second...
With the recent advances in autonomous underwater vehicle (AUV) technology, it has become feasible to deploy AUV fleets as ad hoc networks for coordinated missions such as remote intelligence, area mapping, and tactical surveillance. In these unattended missions, AUVs are typically sent by a central node, such as a submarine, and they move autonomously. Although there is no need for continuous monitoring...
For safe ship navigation, efficient and reliable collision assessment and trajectory estimation are required. This study addresses the problem of collision probability assessment between surface ships considering their maneuver intentions. An extended Kalman filter is used for trajectory estimation, and the collision probability and the probability of intentions are evaluated. The maneuver intention...
Autonomous underwater gliders offer an attractive option for gathering data in the upper ocean because of their relatively easy, flexible, and low cost deployment, operation and recovery. Compared to AUVs that use propellers, autonomy is much longer, at the expense of speed. For this reason, multiple gliders would be required to adequately cover large areas in a short time (e.g. a regional basin at...
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