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Underwater imaging system has been widely applied in varieties and it is desired to recover underwater image using image processing techniques. In this paper, we proposed a fourth order P_Laplace underwater image restoration method based on MSG. Although the fourth order P_Laplace method has been proved that it could effectively reduce the gradient effect, the bright spot effect and color distortion...
Current measurements, the recording of which was once powered by the current itself, is now electronic nearly everywhere. Batteries provide the energy for the electronic systems when the instrument is autonomous and the power required limits the deployment duration more seriously than the data capacity of the logger. There are several strategies that can be used to extend deployment of autonomous...
In the offshore oil and gas fields, facilities decommissioning research has become a very important topic. The offshore oil and gas facilities should be deposit and abandon after stop production. This paper proposes decommissioning method of the offshore platform by studying this problem.
In view of the deep-sea drilling measurement and control system of the current development needs, designed and implemented the deep-sea drilling measurement and control system based on CAN bus. The main board and the expand board all based on STM32, they use CAN bus to communicate. CAN bus has the advantages of good real-time performance, easy to develop, simple link and strong anti-jamming capability...
The complex EOF analysis of ocean surface currents to the Lionrock is investigated using six days' currents data measured by OSMAR in the southwestern Taiwan Straits. The analysis shows that the first three EOF modes account for 89.51% of the variance and are judged to contain the only statistically significant results, and are the main modes. The analysis has also provided insight into the dynamics...
HF over the horizon radar can be divided into sky wave radar and the surface wave radar according to the radio propagation mode. As a new mode, HF hybrid sky-surface wave radar is composed of the ionosphere reflection propagation mode and the surface wave receiving mode. The technique of HF sky wave and surface wave hybrid networking system for HF oceanography radar is presented and analyzed in this...
We address the high peak-to-average power ratio problem in underwater multi-carrier acoustic communications. Recently, a peak reduction technique for the band limited underwater channel proposed using data-independent selection of a pre-specified set of out-of-band adjacent tones. Herein, we propose a data-dependent out-of-band tone selection using the matching-pursuit algorithm and then iteratively...
Due to the special working environment, some problems should be taken into account for calibration of vision system used on autonomous surface vehicle (ASV). This paper discussed the relation between calibration parameters obtained from different distances. After a brief introduction to the imaging model of camera and the classical calibration methods, the relation between the distance from calibration...
Laser-induced acoustic source has become an intense research interest because of its wideband signal components, increased autonomy, flexibility of subsurface and capability of airborne operation. It has large potential applications in undersea surveillance, port monitoring, defense missions and a variety of commercial activities such as target recognition and ocean-graphic survey. Underwater material...
A channel estimation methodology that exploits superimposed pilot sequences for underwater acoustic communication is proposed and evaluated. The proposed scheme first estimates the time-varying channel from the received signal which includes the known superimposed pilot sequence. In a later stage fits the channel response in then fitted to a parametric model that characterizes each channel tap through...
Underwater data collection by using Autonomous Underwater Vehicles (AUVs) is increasing within the oceanographic research community. AUVs are remarkable machines that processed data for gathering local bathymetric information, which have been developed, investigated and utilized for various purposes. In this study, the Iver2 AUV is examined to accomplish location mapping by well-planned trajectory...
Taking planar phased array for example, the beam patterns for sonar array installed in different positions are studied using the finite element analysis software ANSYS and the acoustic software SYSNOISE. The conditions that the sonar array is installed parallel to the vessel, parallel to the acoustic window and the sonar array is installed at different distances from the acoustic window are considered...
This paper proposes an UKF(unscented Kalman filter) method for localization and sea level estimation of an underwater vehicle. The method uses the information of both the seabed geometry and depth of the vehicle from sea surface. Since the sea level fluctuates with time due to tide, wave, and precipitation, depth of the vehicle and range data to seabed sometimes mislead the location estimation. If...
In this paper, authors have focused on safety and uniformity as the basis of utilization system for digestive sludge from marine biomass. At first, when marine biomass is used as materials of methane fermentation, safety and uniformity problems of digestive sludge are investigated. Furthermore, in order to solve the problem, a method of extracting useful materials is examined experimentally.
In this paper we establish a packet loss model which meets the packet loss characteristics of underwater acoustic channel by pool experiment, so that we can simulate the packet loss characteristics of underwater acoustic channel on the computer, save the time for sea trial. In the proposed model, the Gilbert-Elliot model is used to simulate the packets loss. What's more, studied speech and image business...
A hybrid underwater glider Petrel-II is presented in this paper. It combines behaviors of traditional autonomous underwater vehicle and those of autonomous underwater gliders. It can dive along a saw-tooth trajectory in the gliding mode and autonomously cruise in the level-flight mode. It is characterized by long endurance, long fight range, high cost efficiency, and good maneuverability. The hydrodynamic...
In situ marine algae detection is very important for many global issues. Even though polarized-light scattering has the promising application in the biomedical characterization, its potential to detect marine algae is still not clear. The movements of the suspended marine algae due to their own migrations, arise challenges for the polarization measurement and information acquisition. In this paper,...
The circulation in Singapore coastal waters is driven by the variable tidal forcing of the surrounding seas, complex bathymetry, irregular coastlines, and seasonal monsoon and local winds. An unstructured-grid SUNTANS model is employed to perform three-dimensional simulations of flow in Singapore coastal waters. The model is tidally forced at the open boundaries with tidal constituents as derived...
Study results derived from global tide gauge data indicate that the global waters were simultaneously subject to the modulation of lunar nodal tide showing a period of 18.6 years and rose at a rate of about 2 mm per year in the past century. In contrast to other regions, those sitting along the east Atlantic Ocean coastal lines show strong semi-diurnal pattern and seemly do not suffer from extraordinary...
High frequency (HF) radar systems are useful for measuring the velocity of sea surface currents. Besides the ecological and economic importance of being able to accurately measure currents, the US Coast Guard uses HF radar to make decisions involved in search and rescue operations. Currently, 5 MHz or long-range HF radar systems output radial vector files that are calculated using a 180-minute averaging...
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