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According to the serious challenge of underwater acoustic detection under low signal-noise-ratio (SNR) conditions, the stochastic resonance (SR) would be likely applied to enhance the detection performance of underwater weak received signals. However, the way of adjusting system nonlinearity, noise intensity or signal structure to match arbitrary noisy signal is still a serious problem which can be...
This paper presents three deep-towed vehicles including the Abyss Twisted-pair Imaging System (ATIS), the Fiber-optical Instrumentation Towed System (FITS), and the Video-guided multi-corer (V-Corer), which were developed under the National Energy Program (NEP) of Taiwan from 2013 to 2016. Both of the vehicles ATIS and FITS were designed mainly for seafloor imaging but with different power and communication...
During an expedition to the Atlantic Mid-Ocean ridge in August 2016, an underwater hyperspectral imager (UHI) was utilized. The target was to investigate its applicability to exploration for marine minerals. The imager was deployed on both an autonomous underwater vehicle (AUV) and a remotely operated vehicle (ROV). To the authors knowledge, this is the first time a full scale hyperspectral imager...
Ultra-Short BaseLine (USBL) positioning systems born as a technology for underwater target tracking from a vessel. Despite they are commonly and efficiently used for this purpose, the recent literature about navigation of Autonomous Underwater Vehicles (AUVs) demonstrates that they can represent a valuable support for these systems. Measurements of the AUV position can be exploited as observations...
This paper describes the ongoing work of the authors in translating two-level system design techniques used in Health Informatics to the Earth Systems Science domain. Health informaticians have developed a sophisticated two-level systems design approach for electronic health documentation over many years, and with the use of archetypes, have shown how knowledge interoperability among heterogenous...
In this paper, we continue the discussion about of fast numerical simulation of tsunami wave propagation. In case of seismic event offshore Japan, tsunami approaches the nearest shore in approximately 20 minutes. As the calculation of tsunami wave propagation normally serves as a part of any warning system, speeding up this software results in overall better performance for tsunami warning. Implementation...
Any Tsunami Early Warning System (TEWS) should provide reliable prediction of the wave parameters as early as possible. Numerical calculation of the tsunami wave propagation over the particular part of the ocean can be implemented rather efficiently using modern high-performance system. It is possible when the initial wave shape at tsunami source is given. In this paper we discuss and show the fast...
Underwater manipulation is an essential operation for performing a diverse range of applications in the submerged environment that, in spite of the hostile and unstructured environment, it requires high precision and reliability of the robotic arm. The paper presents the evaluation and characterization of the kinematic performances of an underwater robotic arm mounted on a light work class ROV. The...
In this paper, we investigate the performance of HFM signals for timing synchronization in underwater acoustic communication systems. The considered HFM signals are comprised of up-sweep and down-sweep HFM signals having different bandwidth. The synchronization performance of the proposed HFM is then evaluated numerically using the channel model constructed based on western sea of South Korea. Numerical...
In order to detect quiet submarines, an important trend in underwater acoustics is the use of large arrays with many elements in an effort to detect weak signals. In recent years, vector sensors have been widely used in sonar equipment. Compared with sound pressure array, vector array can be used to expand array aperture to improve processing gain, and overcome the problem of left and right ambiguity...
Self-calibration methods of underwater light attenuation using a multispectral imaging system are important for subsea detection. However, the accuracy of calibration is strongly related to the characteristics of color filters used in imaging systems. This paper presents the influence of filters on attenuation calibration. The principle of a self-calibration method is introduced with the origin of...
In this work, the control framework of the DexROV Horizon 2020 project is presented. The framework is based on the task priority concept, extended by the authors to allow the activation and deactivation of tasks. The general concepts of control objectives, task and actions are given. The execution of a pipeline's weld inspection is used as study case to test the proposed framework in a simulation...
In this work we describe an experimental investigation into wideband channel models for acoustic wave propagation in rigid and elastic pipelines operating over the 1∼50 kHz frequency band. We provide frequency domain transfer function measurements for both rigid and elastic pipes, from which time domain responses of the pipeline channel can be calculated. Narrowband impulse responses are studied to...
This work is aimed at exploring characteristics of horizontal refraction in three-dimensional sound propagation. The horizontal refraction angle is used as the indicator for evaluating strength of horizontal refraction effects. The horizontal refraction angle, as well as the sound fields, in a series of wedge-shaped ocean waveguides with different bottom parameters are simulated. Furthermore, the...
In this paper, a grid-based matching multiple sources localization (MUSOL) method is proposed and a spatial spectrum about multiple sources positions is obtained. The spatial spectrum obtained by MUSOL can provide a visualization results about the possible region of the multiple sources positions only if the AOA measurements have the right data association. This property permit the MUSOL not to perform...
For a better understanding of the air-sea interactions that occur during typhoons and improved accuracy in typhoon forecasting, the Institute of Oceanography at the National Taiwan University has developed a buoy that can measure meteorological and hydrographic conditions, and transmit the high-precision data in near real-time. The buoy captures various types of meteorological data, including air...
Over the last nine years three major research studies have led to the development of a new design of nylon rope suitable for permanent moorings with design lives in the region of at least 20 to 30 years. Prior to this research nylon rope designs had a fatigue performance which was only adequate for temporary moorings typically lasting six months to a few years. This paper reviews two pivotal very...
This paper describes the specific challenges to measure the ocean currents in the narrow channel of the Raz Blanchard by means of an ocean radar pair. The ocean current velocities in this area are extreme high, up to 5 m/s and are changing fast. In addition to this, the ocean wave parameters should be measured as well. These boundary conditions are challenging for any oceanographic measurement equipment...
We present the total particulate, non-algal and phytoplankton spectral absorption coefficients measured via the quantitative filter technique in a spectrophotometer with integrating sphere. Chl-a primary and secondary absorption peaks evident in the particulate absorption spectra, exhibited dominant influence of phytoplankton pigments on the total particulate absorption spectra. Additional peaks and...
The present research in underwater robotics aims to increase the autonomy of manipulation operations in fields such as archaeology or biology, that cannot afford costly underwater interventions using traditional Remote Operated Vehicles (ROV). This paper describes a work towards the long term goal of autonomous underwater manipulation. Autonomous grasping, with limited sensors and water conditions...
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