Buoy System Research Articles

Efficiency of different collectors for spat settlement of Mediterranean mussel (Mytilus galloprovincialis) in the southeastern Marmara Sea, Türkiye

ABSTRACT Mediterranean mussel have spread almost throughout Turkish seas. The objective of this study was to set up longline systems to determine spat efficiency by two different systems (buoy and pipe) consisting of three different materials, new rope, used rope and used net, in Erdek Bay. The second objective was to identify whether waste materials could be used in mussel culture. Sea water temperature, salinity, dissolved oxygen, chlorophyll-a, total suspended, inorganic and organic matter were measured at monthly intervals. Results revealed that the highest settlement (4196 spat) was observed in the collectors made of used nets in the pipe system (October 2016). In contrast, the lowest value (2 spat) was recorded from the collectors made of new ropes in the buoy system (August 2016). Waste materials presented relatively better results on settlement than the new ropes. The optimum production was observed in the mussel farm with 1239 spat in the buoy and 1607 spat in the pipe systems, which were commissioned in April 2016. It is concluded that the spat performance was affected by collectors and materials. Therefore, we propose the use of used ropes and used nets, which will allow more effective attachment surfaces to achieve higher spacing settlement.

Effects of different culture methods on growth, meat yield, and nutritional composition of Mediterranean mussels (Mytilus galloprovincialis), south side of Marmara Sea, Türkiye

This study, conducted between February 2016 and October 2017 on the coast of Erdek in the Marmara Sea, established two longline systems (buoy and pipe). Monthly growth rates of juvenile mussels placed in polyethylene and polyamide nets within these systems were monitored. The monthly chemical composition and meat yield of mussels that reached harvest size were analyzed in both systems. Environmental parameters were measured monthly to assess environmental conditions. The highest meat yield of harvested mussels was recorded in January, with values of 36.99 ± 0.72% for mussels cultured in the pipe system and 31.43 ± 1.82% for those cultured in the buoy system. The highest growth in mussels was achieved in the group cultured in the pipe system within polyamide nets. The December sample showed the highest moisture content of 83.98% and the highest ash content of 2.34%. The highest crude fat content was found in the September sample. The June sample had the highest protein content. The Black Sea, Sea of Marmara, and Aegean Sea offer suitable areas for mussel cultivation. Currently, mussel farming is conducted in these areas, producing tens of thousands of tons annually. This publication contributes to the expansion of the production process.

Advanced Moored Data Buoys for Catching Typhoons in the Western North Pacific

Abstract With the western North Pacific being one of the most active typhoon hotspots, a reliable buoy system is essential for in situ observations during typhoon passages. This study details the development and implementation of two improved buoys designed by National Taiwan University based on the Autonomous Temperature Line Acquisition System. It aims to establish a buoy network for near real-time, high-resolution meteorological and oceanic data collection during typhoon periods in the western North Pacific. The buoy system was distinguished by its reliable design, low power-consumption system, dual satellite and radio communication system, and inductive modem-based data acquisition system. Moreover, the system was proven robust to extreme weather conditions and fishing challenges. From 2015 to 2022, we conducted sea trials in typhoon hotspot regions every summer (normally June to October), demonstrating the buoys' durability and capability to withstand 21 typhoons while collecting valuable scientific data.

Oblique wave interaction with dual submerged oscillating buoy as WEC near a partially reflecting wall

The hydrodynamic performance of a submerged dual cylindrical wave energy converter (WEC) in front of a partially reflecting vertical wall is investigated within the framework of linear wave theory. The double cylinders are fully submerged and are constrained only in heave motion. The conversion of wave action into usable power occurs by the coordinated motion of two buoy systems viz. a power take-off mechanism (PTO). The numerical solution for the boundary value problem comprising of wave diffraction and radiation by submerged dual cylinders is obtained using the Boundary Element Method (BEM). The study is devoted to investigating the influence of various factors, the effect of cylinder dimensions, cylinder-cylinder spacing, partially reflecting wall-cylinder distance, angle of wave attack, and its submergence. The compelling results are presented by examining the heave force, surge force, response amplitude operator (RAO), damping factor, and particular interest in the WEC energy capture efficiency under distinct seawall reflections. The study reveals that there is an increase in the WEC efficiency by ≈12% in the case of a dual cylinder compared to a single cylinder. Besides, the amplification of the WEC efficiency is ≈78% for the case of a fully reflecting wall compared to the WEC in the open fluid domain. The present study will further help to understand the dynamics of WECs integrated into protecting shore structures such as breakwaters, groins, and seawalls.

Non-intrusive wave measurement device for accurate analysis and real-time data

This research aims to enhance our understanding of wave climate in ocean wave studies by creating a buoy-based system equipped with gyroscopes and accelerometers. This system allows for accurate measurement and analysis of ocean wave profiles, with primary objectives including the conversion of wave heave motion into electricity and forecasting wave strength for coastal erosion evaluations. The study's main goals encompass the development and integration of gyroscopes and accelerometers into the buoy system, the deployment of the device to collect wave profile data, and the analysis of this data using specialized software. The research culminated in the successful creation of a buoy capable of accurately measuring wave acceleration, velocity, and displacement with an approximate accuracy of 90%. This significant accomplishment advances ocean wave research and offers vital insights for sustainable coastal management, ultimately bolstering our grasp of wave climate and promoting informed decision-making and effective strategies to counter coastal erosion.

Analisa Pembangkit Listrik Tenaga Ombak di Daerah Pesisir Jakarta Utara

Electrical energy is energy that is really needed in modern times like now. As the population increases and the economic activity of the population increases, consumption of electrical energy increases. To overcome this problem, namely by creating a power plant with renewable energy, one example is a wave power plant. Wave power plants are plants that rely on wave energy to produce electricity. The aim of this research is to analyze the performance of wave power generators using a buoy system in the coastal area of ​​North Jakarta. By carrying out a total of 10 days of testing in 2 different places, namely Mutiara Beach and Wika Beach, all in North Jakarta. This wave power generator with a buoy system is capable of producing the highest electrical power of 24.9 volts when using a tube-style buoy at Mutiara Beach, while the lowest power is obtained when using a beam-style buoy, namely 6.65 watts at Wika Beach.

Self-powered ocean buoy using a disk-type triboelectric nanogenerator with a mechanical frequency regulator

Triboelectric nanogenerator (TENG) systems have been demonstrated to generate power with high density. However, the electrical output power obtained from wave energy harvesting using TENG systems is typically limited to several milliwatts. To address this limitation and support various ocean buoy systems, an efficient method to scale-up TENG systems is required. In this paper, we present a self-powered ocean buoy (SPOB) incorporating a disk-type, soft-contact, mechanical frequency regulator TENG (DSMFR-TENG). The mechanical frequency regulator (MFR) enables the conversion of low-frequency wave energy to high-speed mechanical rotation, facilitating high power generation with the disk-type TENG. The SPOB was tested in a wave tank, reaching a peak power output of 470 mW and an average power output of 130 mW after the MFR released the rotational energy. To further enhance the functionality of the buoy, the DSMFR-TENG and a microcontroller, temperature sensor, and acoustic transmitter were integrated with the SPOB. The acoustic transmitter successfully transmitted signals 7, 23, and 30 times over a one-minute period at wave frequencies of 0.33 Hz, 0.5 Hz, and 1 Hz, respectively, thereby demonstrating the power supply capability of the TENG system for ocean buoys.

Indigenization of Buoy Components Using Additive Manufacturing Technique

The Ocean Observation Systems (OOS) group of the National Institute of Ocean Technology (NIOT) is involved in the design, development and sustenance of moored data buoys in the Indian Seas. The moored buoy systems deployed in the Northern Indian Ocean provide real-time, continuous observation of surface meteorological and oceanographic parameters which help in monitoring extreme weather events and natural disasters such as cyclones and tsunamis. Buoy components are of different sizes and shapes and are made of various materials, including metals and plastics. However, due to unique and critical design requirements, the development of deep-sea components faces hurdles caused by manufacturing limitations. The advent of additive manufacturing (AM) has met the demand for quickly producing parts. Due to the high pressure and low temperature conditions, it is extremely difficult to design and develop deep sea components. Consequently, High Impact Polystyrene (HIPS) material has been selected for the subsurface floats. The float is manufactured using the Fused Deposition Modeling (FDM) additive manufacturing technique in the Fabheads 1K FDM printer with pellet based extrusion method. These subsurface floats are used at a water depth of 500 m in NIOT buoy systems, with a working pressure of approximately 50 bar. Taking a factor of safety of two into account, the part is designed to withstand 100 bar. To assess the component's performance under deep-sea hydrostatic conditions, it underwent testing in the hyperbaric chamber test facility at NIOT. During the qualification process, the component successfully withstood the design pressure of 100 bar and imploded at 102 bar. This study is part of NIOT's ongoing efforts to indigenize deep-sea components using AM and assess its future prospects.

A numerical and experimental study of a buoy interacting with waves

PurposeThis paper aims to report the study of a fluid buoy system that includes wave effects, with particular emphasis on validating the numerical results with experimental data.Design/methodology/approachA fluid–solid coupled algorithm is proposed to describe the motion of a rigid buoy under the effects of waves. The Navier–Stokes equations are solved with the open-source finite volume package Code Saturne, in which a free-surface capture technique and equations of motion for the solid are implemented. An ad hoc experiment on a laboratory scale is built. A buoy is placed into a tank partially filled with water; the tank is mounted into a shake table and subjected to controlled motion that promotes waves. The experiment allows for recording the evolution of the free surface at the control points using the ultrasonic sensors and the movement of the buoy by tracking the markers by postprocessing the recorded videos. The numerical results are validated by comparison with the experimental data.FindingsThe implemented free-surface technique, developed within the framework of the finite-volume method, is validated. The best-obtained agreement is for small amplitudes compatible with the waves evolving under deep-water conditions. Second, the algorithm proposed to describe rigid-body motion, including wave analysis, is validated. The numerical body motion and wave pattern satisfactorily matched the experimental data. The complete 3D proposed model can realistically describe buoy motions under the effects of stationary waves.Originality/valueThe novel aspects of this study encompass the implementation of a fluid–structure interaction strategy to describe rigid-body motion, including wave effects in a finite-volume context, and the reported free-surface and buoy position measurements from experiments. To the best of the authors’ knowledge, the numerical strategy, the validation of the computed results and the experimental data are all original contributions of this work.

An Automatic Internal Wave Recognition Algorithm Based on CNN Applicable to an Ocean Data Buoy System

The application of internal wave recognition to the buoy system is of great significance to enhance the understanding of the ocean internal wave phenomenon and provide more accurate data and information support. This article proposes an automatic internal wave recognition algorithm based on convolutional neural networks (CNN), which is used in the tight-profile intelligent buoy system. The sea profile temperature data were collected using the Bailong buoy system in the Andaman Sea in 2018. The CNN network structure is applied to feature compression of ocean temperature profile data, reducing the input feature amount of the feature recognition network, thereby reducing the overall algorithm parameters and computational complexity. By adjusting the number of convolution kernels and the length of convolution steps, the original data features in the time domain and the space domain are compressed, respectively. The experimental results show that the identification accuracy and robustness of this method are clearly superior to those of other methods. Additionally, the parameter number and calculation amount of this algorithm are very tiny, which greatly improves the possibility of its deployment in the buoy system.

Performance of a two-body heaving cylindrical wave energy converter on stepped sea bottom

The present study deals with the surface gravity wave interaction with a heaving dual concentric cylindrical wave energy converter (WEC) buoy system on the stepped sea bottom. The energy captured by linear electric generator (LEG), is directly proportional to relative heave motion of the present WEC buoy system. In the present study, the analytical diffraction and radiation problems are solved using the Fourier–Bessel series expansion method and matched eigenfunction expansion method (MEFEM) under the assumption of small amplitude water wave theory and structural responses. Wave exciting force acting on both vertical cylinders is obtained. The role of the step type bottom on the relative heave response amplitude operator (RAO) of the buoy system, is analyzed for various structural configurations and wave characteristics. A series of experiments are carried out in a two-dimensional wave flume both with and without the presence of step-type bottom. The computed results are in good agreement with the experimental results. It is found that the inclusion of artificial step at the sea bottom leads to higher wave energy harnessing. The findings of the present study are likely to be of immense help in the design and development of various point absorber-type WEC buoy systems.

Design and Optimization of PV Power Supply System for Marine Buoys

Marine buoys need to operate in high sea areas far from land for a long time. Therefore, how to provide a long-term power supply for the buoy system is critical to be addressed. Photovoltaic (PV) power supply systems are the most commonly used power supply method for marine buoys. Due to the limitations of the buoy structure and considering the rotation of the buoy in the ocean, most of the PV modules are placed in a four-sided enclosure. The output performance of the PV power supply system in this placement is affected by the tilt angle produced by waves. However, there are few relevant studies on the actual power generation performance of PV power supply systems for marine buoys, and there is a lack of methods for power generation performance analysis. In order to meet the power requirements of the marine buoy, a large design margin must be left. It increases the cost of marine buoys. In this paper, second-order Stokes waves are used to simulate waves of different levels by varying the wave height and frequency. The motion characteristics of the marine buoy are analyzed using ANSYS-AQWA under calm-rippled, smooth, slight, and moderate conditions. Combined with the tilted surface irradiance calculation model to get the variation law of solar radiation of PV modules under dynamic conditions, the effect of different tilt angle PV modules on the output of PV system under dynamic conditions was also studied. The experiments show that for every 5° increase in the tilt angle of the PV modules the output power of the system decreases by 3% on average. As the tilt angle of the PV modules increases, the impact on the system output performance is more pronounced. The output power decreased by 69.5% when the PV modules were tilted at an angle of 90°, and the PV system electrical parameters were similarly affected. By comparing the influence of different tilt angles on the power supply performance of PV modules, we optimize the design of the PV power supply system of the buoy. This enables the designers to maximize the use of limited area and space while reducing the cost and extending the power supply time and service life of the buoy.

A Distributed Intelligent Buoy System for Tracking Underwater Vehicles

Underwater vehicles play a crucial role in various underwater applications, such as data collection in underwater sensor networks, target detection and tracking, and underwater pipeline monitoring. Real-time acquisition of their states, particularly their location and velocity, is vital for their operation and navigation. Consequently, the development of a remote tracking system to monitor these states is essential. In this paper, we propose a system that can track the underwater vehicle’s location and velocity. We take a systematic approach that encompasses the system architecture, system composition, signal processing, and mobility state estimation. We present the system architecture and define its components, along with their relationships and interfaces. The beacon signal employed in the system features dual-hyperbolic-frequency-modulated (HFM) waveform and an OFDM symbol with cyclic prefix (CP). Based on this beacon signal, we demonstrate how signal processing techniques are utilized to precisely determine the time of arrival and reduce false alarm rates in underwater acoustic channels affected by impulsive noise. Additionally, we explain how the CP-OFDM symbol is used to measure the Doppler scaling factor and transmit essential information for localization and velocity estimation purposes. Utilizing the measurements obtained through signal processing, least squares estimators are used for estimating both the location and velocity. To validate the effectiveness of our approach, we implement the system and conduct field trials. Two separate experiments were conducted in which the diagonal lengths of the square topology were designed to be 1000 m and 800 m. The minimum/maximum root mean square error of localization in the first and second experiment is 2.36/2.91 m and 1.47/2.49 m, respectively. And the minimum/maximum root mean square error of velocity estimation in the first and second experiment is 0.16/0.47 m/s and 0.21/0.76 m/s, respectively. Results confirm the effectiveness of the proposed method in estimating the location and velocity of the underwater vehicle. Overall, this paper provides a practical and effective design of a system to track the location and velocity of underwater vehicles. By leveraging the proposed system, signal processing, and mobility state estimation methods, our work offers a systematic solution. And, the successful field experiment serves as evidence of the feasibility and effectiveness of the proposed system, making it a valuable contribution to the field of tracking underwater vehicles.

A Multi-Objective Optimization of the Anchor-Last Deployment of the Marine Submersible Buoy System Based on the Particle Swarm Optimization Algorithm

Marine submersible buoy systems hold significant value as critical equipment in marine science research. This study examines a marine submersible buoy system that includes an anchor block, mooring line, battery compartment, power supply cable, and submersible buoy. The anchor-last deployment method is a conventional strategy for deploying marine submersible systems. Initially, the other components are positioned on the sea surface, followed by the deployment of the anchor block from the ship’s deck. The anchor block will pull the battery compartment and submersible buoy into the water and eventually sink to the seabed. In this deployment process, ocean currents have a relatively large impact on the anchor block’s landing position. Increasing the weight of the anchor block will make the anchor block land on the seabed sooner, which can minimize the impact of ocean currents. However, an overabundance of weight can generate a significant strain on both the cables, potentially resulting in cable breakage. In order to find the parameters that can make the anchor block reach the seabed as soon as possible and ensure that the tension force of the cables does not exceed the maximum, a dynamic model of the deployment process is established based on computational fluid dynamics (CFD) and solved using the Runge–Kutta method of the fourth order. Particle swarm optimization is employed to optimize the key parameters. The penalty function is used to constrain the particle space. The findings indicate that the utilization of particle swarm optimization is efficacious for optimizing the parameters of submersible buoy systems for marine applications. Optimized parameters allow the anchor block to reach the seafloor quickly and the tension on the cables to not exceed the given value.

Design and Implementation of Inductively Coupled Power and Data Transmission for Buoy Systems

Moored buoys are important components of stereo platforms for ocean observation, which are crucial in underwater exploration. In complex marine environments, power supply and data transmission between moored buoys and underwater sensors are difficult. To solve these problems, an inductively coupled power and data transfer (ICPDT) scheme based on LCCL-S-LC hybrid compensation is proposed. The power transmission was analyzed by establishing an LCCL-S-LC compensation buoy ICPDT system model. The system efficiency and output power were analyzed when the load changed, and the optimal load resistor for maximum system efficiency was determined. A modulation and demodulation circuit used for data transmission was introduced, the compensation topology parameters of each loop of the buoy ICPDT system were deduced, and the crosstalk between power and data was analyzed and reduced. An ICPDT system prototype was built to verify the system’s feasibility and effectiveness when it was powered by 24 V. The LCCL-S-LC topology reduced the interference between data and power transmission. When the measured output power of the system was 61.5 W, the power transmission efficiency was 78.1%, and the data receiving end could achieve correct demodulation when the transmission rate was 100 kb/s.

Research on Target Tracking Simulation System Framework for Multi-Static Sonar Buoys

In the modern war, with the improvement of the target mobility, the increase of the diversity of the target platform, the decrease in the radiation noise of underwater targets, active sonar technology is becoming increasingly important in the underwater target detection. The data processing has also been continuously improved. Especially with the development of information technology in the modern warfare, the target tracking technology is highly valued by various countries around the world, and it has now become a very important field of research. This article proposes a general tracking framework based on the Multi-Static Sonar Buoys System and a variety of tracking algorithms. It lays the foundation for further completing the multi-target tracking simulation system.

Analysis of Sound Fluctuations in Shallow Water in High Sea States

Sound intensity fluctuation plays a significant role in underwater acoustic studies. In this article, an experiment was conducted in the South China Sea using a buoy system that autonomously emitted and received sound signals to obtain data on sound fluctuations under different wind conditions (in windy weather) for about 179 h. Results showed that the fluctuation of the transmission loss in a fixed position reached up to 15–20 dB. Different potential reasons for this transmission loss fluctuation are analyzed. Using the wind speed data provided by the Earth system, the sea surface wave spectrum model, and the bubble layer model, the fluctuation of the transmission loss was simulated based on the modified Ramsurf sound propagation model. The simulation and experimental results were in good agreement with each other. Therefore, the fluctuation of the transmission loss due to wind-generated waves in high sea states should be considered while studying underwater communication, particularly in shallow water with a positive gradient sound velocity profile.

Research on application and cost estimate for building a buoys system for monitoring offshore sea environment

Monitoring our national offshore sea is a Vietnamese willing, aspiration, and essential demand for the State and its people; it is also a demand for people in the world that some countries have deployed it ready. Based on existing studies in Vietnam, similar applications in other countries, and available technical devices/parts on the market, the author seeks, gathers, researches, and investigates each small part of the application; thereby combining and proposing a complete application that is feasible in applied technology to deploy a system of buoys for monitoring hydrology and environment in an offshore sea of Vietnam; toward a system of mobile monitoring stations, collecting various kinds of data out there; synchronised with the digital transformation in the fourth industrial revolution. Simultaneously, with research theories on costs and current legal regulations, the author collects all relevant costs for each small part of the application and concludes with a conclusion as a suggestion. Then, relevant organisations can have an alternative view and propose a deployment in a condition of Vietnam’s budget.

Tracking Control Based on GPS Intelligent Buoy System for an Autonomous Underwater Vehicles Under Measurement Noise and Measurement Delay

This paper deals with the real-time tracking control problem for an autonomous underwater vehicle based on an acoustic-based positioning method, i.e., the so-called GPS intelligent buoy system, which causes inevitable measurement delay. The measurement delay increases the control difficulty and degrades the tracking accuracy. Additionally, the exact modeling for an autonomous underwater vehicle is difficult due to uncertain hydrodynamic parameters. Based on these findings, a model-free control scheme is proposed. In the proposed scheme, the GPS intelligent buoy system provides the position signals without velocity measurements. Considering the measurement noise, a robust exact differentiator is used instead of the traditional numerical differentiation method to obtain the derivatives of position signals, which saves the limited actuator energy of autonomous underwater vehicles. Simulations are performed to verify the validity of the proposed control scheme. The results demonstrate that the proposed control scheme can achieve high timeliness and high tracking accuracy for autonomous underwater vehicles. Compared to the conventional model predictive control, the proposed controller requires 89.7% less average calculation time. In addition, the proposed controller outperforms the conventional proportion-differentiation controller in root-mean-square error by approximately 62.3−80.7%.

Research on the Arrangement Process of Marine Submersible Buoy System based on Computational Fluid Dynamics

This paper establishes the computational fluid dynamics models of marine submersible buoy system. The models use incompressible Navier-Stokes equations, Renormalization-Group (RNG) turbulence model and the fractional areas/volume obstacle representation method. Using the lumped mass mothed to simulate the anchor line and power supply cable. The result show that the great tension forces increase occurs at the moment when the mooring lines was straightened and after a marine submersible buoy system sinks to the sea floor.