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This paper explores the incorporation of false positives and Bayesian updates into the framework of optimal search. Optimal search is an open-loop optimal control framework developed by the US Navy to optimize search and rescue path planning for rapid sweep sensors such as sonar. Although useful as a pre-planning tool, this framework lacks features necessary for online planning, such as quantification...
Marine towed electrical resistivity survey is widely used for various purposes such as underground resources exploration, coastal engineering, archaeological detection, and UXO detection. To improve data quality and resolution, we propose enhanced in-house developed marine towed electrical resistivity survey system. First, hollow-type carbon fiber submersible electric field sensors were developed;...
In this paper, we analyze a compact vector sensor receiver using angle of arrival (AoA) framework which was recently proposed by Fauziya et. al. We demonstrate that this receiver performs better than a scalar receiver at no extra computational cost. The receiver exploits the inherent capability of a vector sensor to provide spatial diversity without the use of a sensor array. The paper also discuss...
The industry state-of-the-art offshore motion compensation is today carried out by offshore cranes equipped with Active Heave Compensation (AHC) systems, meaning that a hanging load is positioned at a certain height above the seafloor, even though the floating vessel carrying both the crane and the load is moving due to wave disturbances. Lately, there has been an increased interest among the industry...
Underwater acoustic sensor network (UWASN) can gather the ocean data such as temperature, salinity, pH, turbidity and dissolved oxygen etc. with the help of underwater sensor nodes. Using the underwater surface gateway, underwater sensor nodes forward the ocean data to terrestrial network for the analysis. These techniques can be used to detect the water-borne disease causing areas. Water-borne diseases...
Underwater object tracking is one of the most essential and fundamental tasks in ocean investigations recent years. In this paper, we try to capture multi-scale retinex (MSR) model as well as the partial least square (PLS) analysis for underwater object tracking. We first make use of multi-scale retinex model to evolve and enhance the partial color constancy from the underwater video sequences, which...
The performance of an automatic target recognition (ATR) system in the context of naval mine detection is severely affected by the underwater environment. Especially in regions with the presence of sand ripples or mine-sized stones the number of false alarms can become unacceptable high, if the detection algorithm does not account for the type of seafloor. Therefore, a robust way of discriminating...
More diverse marine tasks and longer range water missions require the hydrodynamic shape, viz. hull shape, of Autonomous Underwater Vehicles (AUVs) for both efficient design and least resistance. Therefore a systematic design for the hydrodynamic shape of AUVs is needed and necessary to meet the various requirements. In the present work, a hierarchical classification for the hull shape of AUVs was...
The change of the global dynamic performance of a turret-moored FPSO (Floating Production Storage Offloading) with DP (Dynamic Positioning) control is analyzed for two different internal turret locations: bow and mid-ship. Both collinear and non-collinear 100-yr GOM (Gulf of Mexico) storm environments and two cases (mooring-only, with DP control) are simulated. The horizontal trajectory, 6DOF (degree...
Based on the change-of-coordinates that was previously proposed in [1], in this paper, the wave spectrum inversion problem is solved with very high accuracy for the case when there is little or no noise in the second-order Doppler spectrum. The new solution is based on the form of the forward problem, which is a sum of spatially-dependent linear convolution and cross-correlations. This sum can be...
Blind sailors often rely on sighted guides to convey information while sailing. This information includes the location of other boats, buoys, or obstacles. However, certain types of races — such as match races — do not permit sighted guides on the vessel. Students and faculty from Olin College of Engineering are collaborating with visually-impaired sailors and sighted guides at Community Boating Incorporated,...
This paper presents a concept for a heterogeneous unmanned team designed for autonomous persistent inspection of offshore wind turbines. This team consists of an unmanned surface vessel (USV) and an unmanned aerial system (UAS) operating cooperatively. We describe a concept of operations (CONOPS) in which the USV acts as a ground control station (gCS) for the UAS. The USV shuttles the UAS between...
This paper introduces a sparse subspace method (SSM) for wideband direction-of-arrival (DOA) estimation. SSM is a subspace method in the sense that it follows the idea of focusing presented by a coherent signal-subspace method (CSSM), but different from CSSM, it has no requirement of the preprocessing of an initial DOA estimation. In the meantime, SSM is a sparse method as a result of employing a...
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...
The changes of the seafloor environment caused by natural disasters and human activities greatly shorten the life span of the subsea optical cable. It is urgent to carry out routine inspection and maintenance for subsea cables. In this paper, an automatic inspection system to address these problems is proposed where the localization and inspection mission is conducted by an autonomous underwater vehicle...
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.
The Ocean Observatories Initiative (OOI) is directed to operate and maintain arrays of moored and mobile assets in six locations around the globe. These locations include two coastal arrays off of the east and west coasts of the United States and four global arrays in the Southern Ocean, Argentine Basin, Irminger Sea, and North Pacific. These arrays are currently operational, supplying oceanographic...
Underwater sound source position is determined using a line array. However, performance degradation occurs owing to a multipath environment, which generates incoherent signals. For this reason, the system needs advanced signal processing such as high-resolution beamforming. In this paper, a hydrophone array is proposed for position estimation robust to a multipath environment using generalized cross-correlation(GCC)...
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...
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