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The Nankai trough is one of the largest and hazardous seismogenic zones in the world. Around the Nankai Trough, there are 3 mega thrust earthquake seismogenic zones such as the Tokai, Tonankai and Nakai seismogenic zones. Especially, the estimation of seismic linkage between the Tonankai and Nankai seismogenic zone is very important and indispensable for the reduction of earthquake and tsunami damages...
In this article, we present a novel underwater monitoring system based on the hyperspectral imager. This system consists of the commercial hyperspectral camera and white-colored LED lighting. We evaluated the performance of the proposed hyperspectral imaging system by conducting the small scale experiments to identify the difference of two different oil samples. For the classification between oil...
Studying on ocean ambient noise is important for understanding noise generation and propagation for designing sonar processing systems. Based on the reciprocity of the sound field, a model of distant shipping noise in range dependent environments is described in this paper. The complex pressures are calculated using a parabolic equation (PE) model. The properties of the shipping noise over a deep...
Artificial upwelling is supposed to be a general technique to enhance the marine primary productivity and fishery resources by means of pumping the nutrient-rich deep ocean water (DOW) to the euphotic layer. The wave energy is the most conspicuous form of ocean energy, the extraction of energy from the waves can be a viable economic solution to the power requirements of artificial upwelling. To extract...
A new cooling water system for power plant is proposed in which the cooling medium circulates in the closed duct system between the condenser and the heat exchanger installed at deep sea. This cooling system could improve power generation efficiency since deep sea water has lower temperature than surface water. It is also expected that the environmental impacts on the ocean surface layer will be greatly...
It is important to estimate the multipath time delay in underwater communication and target positioning. Based on the good time delay resolution, wideband signal is used to estimate time delay conventionally, in some situation, it is hard to use wideband signals. Focused on the narrowband signal multipath time delay estimating, an algorithm based on spectral subtraction in logarithm domain was proposed...
This study includes several computational fluid dynamic simulations of wave tanks which employ a geometry designed to create Helmholtz resonance to increase the wave height and fluid velocity. The goal is to create an ideal wave tank geometry for wave energy harvesting, as an increase in the velocity will increase the volume flow rate through the turbines, and therefore power output. Several 2-dimensional...
A submersible digital holographic microscope (DHM) Holoflow@Sea was deployed during AWA fisheries surveys conducted in March 2013 and 2014 in the large upwelling ecosystem of the Canaries Current. The microscope collected about half a million of holograms of microorganisms and other particles suspended in the water column. Selected new results of reconstruction of phyto- and zooplankton species using...
This paper presents an underwater environment monitoring system, which is designed for deployment with a meteorological mast in the offshore wind farm. The factors of safety, reliable, and extendable capacity are the major design concept. First of all, the demonstration project of the offshore wind farms at Taiwan is going to build three pilot wind farms and meteorological masts. The measurement of...
DONET (Dense Ocean-floor Observatory Network for Earthquakes and Tsunamis) is a submarine cabled real-time seafloor surveillance infrastructure for earthquake activity at assumed focus region of mega-thrust earthquake around Japan. The original system DONET1 was constructed in To-Nankai earthquake focus region and twenty seafloor observatories are working in operation beginning in 2011 to contribute...
During deep sea exploration, the motion of the deep tow system is influenced by that of the surface vessel, the change of the cable length and the current field in the water column. Though the towing vessel moves in a straight line on the sea surface, the heading of the tow body is not necessary collinear to the towing direction. If no devices are available to adjust the direction of the tow body,...
The low cost moored system KdUINO allows to measure parameters related to water transparency, specifically the diffuse attenuation coefficient parameter. In this contribution, its measurements are compared with other high precision scientific commercial instrument in order to estimate the sensor measurement error.
High swell is often generated offshore and damages the east coasts of Korea and accidents, a correct prediction of dangerous swells should be done before they approach to the shore. Recently, a warning system to countermeasure dangerous swells is setup on the east coast of Korea with simultaneous in-situ wave measurements at the northeast site of Ulleung offshore island and at Hupo nearshore station...
Improvements to a method of seafloor roughness measurement using low-power lasers and a video recorder mounted on a remotely operated vehicle (ROV) are presented. The platform is a Saab Seaeye Falcon observation class ROV. Six green laser beams are spread into illuminated planes using gratings or cylindrical lenses. The intersection of the laser planes with the ocean bottom was imaged on a high-definition...
The CODAR is a High-Frequency (HF) radar system. Recently, CODAR becomes widely used for monitoring ocean surface currents remotely in nearly real time. However, some environmental effects often hampers or weakens the strength of CODAR system, which would deteriorate the data quality of CODAR and result in missing data in the designated observation region. In this study, we analyzed complete CODAR...
Pulse propagation in the surface duct with the source far below the duct is analyzed. Experimental results show that through the duct, the sound can propagate to the range much farther than that predicted by the ray theory. Besides, the propagation range is strongly related with the signal frequency. This propagation path is reproduced using the normal mode model. Furthermore, the ray representation...
The development of a graphical user interface for a hydrocarbon sensor network system is presented in this paper. The software introduces two mathematical algorithms for realtime data processing and visualization: The Kalman filter is employed to remove spikes from acquired data; PCA (Principal Component Analysis) is used to reduce the dimension of the multiple sensor dataset and project the dominating...
Forward scattering is a special phenomenon for bi-static sonars, and it has received much attention in recent years because it can provide a lot of useful information for estimations. In this paper, two kinds of speed estimation method are proposed for forward scattering. Very simple geometrical principles are used in the two methods, and the complex acoustic field is not needed to be calculated when...
This paper addresses the problem of automatic learning of statistical models of clicks for odontocete species classifications, particularly focusing on improving accuracy of the classifier by iteratively identifying click-like sounds that are likely to be noise and removing these from the model training set. The algorithm is weakly supervised in that no hand-labeled click regions are available, but...
This paper shows that a comprehensive multivariable approach of autopilot design that mixes sliding mode and PID leads to robustly satisfactory results for underwater mobile robot. The 6-DOF linear equations of motion can be divided into three subsystems for speed control, steering, and diving. The sliding mode algorithm is designed for steering control and PID is used for diving and speed control...
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