Light Buoy Research Articles

The Effect of Illumination, Electrode Distance, and Illumination Periods on the Performance of Phototrophic Sediment Microbial Fuel Cells (PSMFCs)

Microbial fuel cells (MFCs) can potentially be used to overcome issues with battery powered light buoys and their frequent maintenance. In this study, a phototrophic sediment microbial fuel cell (PSMFC) was chosen, as the microalgae provide oxygen to be reduced on the cathode and to release the necessary nutrients for the bacteria on the anode. To achieve this, we studied the effect of illumination, the period of the illumination, and the distance between 9-cm2 stainless steel mesh electrodes on the performance of the MFC. The illuminated cells were able to produce higher OCP (max. 205.2 mV) and higher power density (max. 0.68 mW/m2). However, the highest current was achieved during the unilluminated variation (max. 5.3 μA unilluminated and 3.3 μA illuminated). Prolonged illumination produced a higher OCP, current, and power density. A longer electrode distance produced a higher OCP, power density, and current. SEM analysis showed that biofilm formation tended to be scattered at lower electrode distance and more clumped (filling the anode area) at higher electrode distance. Through FTIR analysis, it was found that all MFC variations had the same organic matter, but a more concentrated organic content was found in the MFC at longer electrode distances.

Ship Path Planning Based on Buoy Offset Historical Trajectory Data

In the existing research on the intelligent navigation of ships, navigation route planning often regards light buoys as fixed obstructions. However, due to factors such as water ripples, the position of the buoys keeps periodically changing. If the buoys are set to a fixed range of avoidance areas in the process of ship navigation, it is easy to allow a collision between the ship and the light buoys. Therefore, based on historical motion trajectory data of the buoys, a SARIMA-based time-series prediction model is proposed to estimate the offset position of a given buoy in a specified time. Furthermore, the collision-free path planning approach is presented to dynamically recommend an accurate sailing path. The results of the simulation experiment show that this method can effectively deal with collisions of ships caused by the offset position of the light buoys during the navigation of the large and low-speed autonomous ships.

The Offset Position Prediction of Light Buoy Based on Grey Optimization Multiplicative Seasonal Model

Light buoy is a navigation aid sign to guide ship navigation, which plays an important role in ensuring the safety of ship navigation. To predict the offset distance of light buoy and provide accurate position information of light buoy for ship navigation safety, and to solve the problem of low prediction accuracy caused by the excessive amplitude of initial training data in the traditional multiplicative seasonal model, a grey optimization multiplicative seasonal model is proposed. By analyzing the characteristics of the time series of the light buoy offset data, as well as the regularity and seasonal characteristics of the light buoy offset distance, an optimization model is established. Based on the real offset distance data of the 1 # light buoy in Meizhou Bay, the model is simulated, and the prediction accuracy of the model is evaluated by MAPE, RMSE, and the Monte Carlo sampling method. The results show that, compared to the traditional multiplicative seasonal model, the average absolute percentage error of the grey optimization multiplicative seasonal model is reduced by 6.66%, and the root mean square error is reduced by 2.96. It shows that the model can effectively deal with the problem that the error of the prediction results caused by the instability of the initial time series of the traditional multiplicative seasonal model is too large, which provides a new idea for the prediction of the offset distance of the light buoy and the navigation safety of the ship.

The Offset Azimuth Prediction of Light Buoy Based on Markov Chain Optimization Multiplicative Seasonal Model

Aimed at the problem of the large error caused by uncertain factors in the fitting process of the traditional multiplicative seasonal model, the advantages of the Markov chain in this study are applied to the multiplicative seasonal model to optimize the prediction results. Based on the residual value between the theoretical and actual values, the values of different intervals are divided into states. The transition probability matrix is established through different probabilities; then, the weighted sum of different prediction probabilities is carried out to select the optimal prediction state. The real number of Meizhou Bay portlight buoys is used to verify the prediction effect of the model, and MAE, MAPE, RMSE, RRMSE, SSE, R2 are used to calculate the error between the predicted value and the actual value. The results show that compared to the traditional multiplicative seasonal model and other prediction models, the prediction MAE of the MC-SARIMA model is decreased by 2.19003794, the MAPE is decreased by 0.66%, the RMSE is decreased by 2.092671823, the RRMSE is decreased by 0.006221352, the SSE is decreased by 404.0231931, and the R2 is increased by 0.224686247. It shows that the multiplicative seasonal model optimized by the Markov chain can predict the azimuth data of the light buoy more effectively than the traditional multiplicative seasonal model and other prediction models.

Development of Rechargeable Seawater Battery Module

Rechargeable seawater batteries (SWBs) use Na+ ions dissolved in water (seawater or salt-water) as the cathode material. They are attracting attention for marine applications such as light buoys, marine drones, auxiliary power for sailing boats and so on. So far, SWB design has been developed from the coin-type to prismatic-shape cell for research purposes to investigate cell components and electrochemical behaviors. However, for commercial applications, that generally require >12 V and >15 W, the development of an SWB module is required, including cell assembly and packing design. The purpose of this work was to conduct research on the SWB cell assembly method while considering the SWB’s properties and minimizing current imbalance. Additionally, a 5 Series (S) 4 Parallel (P) SWB module is constructed and validated using commercially available light buoys (12 V, 15 W).

Numerical Investigation of Hydrodynamic Performance of a Light Buoy With Different Mooring Configurations in Regular Waves

Abstract The single-moored light buoys employed in the lower reaches of the Yangtze River play an important role in indicating ship navigation and ensuring safety. To clarify the interaction between waves and floating buoys moored to the riverbed, this paper applies a numerical approach to investigate the wave-induced motion performance of a light buoy and reveal the effects of different mooring configurations to extend its service life. An open-source smoothed particle hydrodynamics (SPH)-based numerical model named dualsphysics coupled with MoorDyn is implemented. This coupled model is validated by simulating the motion of a moored rectangle buoy in regular waves, and compared with experimental data and the numerical results of reef3d code, a mesh-based computational fluid dynamics (CFD) model. The validation results show that the coupled model reproduces experimental data well and has a smaller deviation in comparison with reef3d. Then, the coupling model is applied to simulate the hydrodynamic performance of the real-size light buoy employed in Yangtze River and investigate the effects of encounter angle between wave propagation direction and mooring chain. The results demonstrate the capability of this coupled mooring model to simulate the motion of a moored buoy in regular waves, and this numerical approach will be extended to simulate the light buoy in more complex environments such as irregular waves, flow or extreme weather in further work.

Ferromagnetic Liquid Droplet on a Superhydrophobic Surface for the Transduction of Mechanical Energy to Electricity Based on Electromagnetic Induction.

Ferromagnetic liquids undergo reversible magnetization changes upon varying external magnetic field levels. The movement of ferromagnetic liquid droplets across a coil under an external magnetic field holds promise as an energy transducer from mechanical force to electricity; however, it suffers from an adhesive issue between the ferromagnetic liquid and the solid pedestal. We introduce a superhydrophobic support that uses antiwetting surfaces to remarkably reduce adhesion during the movement of ferromagnetic liquid droplets. Maxwell numerical simulation was utilized to analyze the working mechanism and improve further electrical outputs. By controlling the droplet size, the strength of the magnetic bottom and the tilting speed of the test condition, we generated a ferromagnetic liquid droplet-based superhydrophobic magnetoelectric energy transducer (FLD-SMET) that can convert vibrational energy to electricity. When a 100 μL ferromagnetic liquid droplet was used for FLD-SMET under a 13 mT magnetic field, an electrical voltage response of 280 μV and electrical current response of ∼7.5 μA were generated using a shaking machine with a tilting speed of 9.5°/s. We thus show that such a device can serve as a self-powered light buoy floating on a water surface. Our study presents an applied concept for the design of droplet-based energy harvesters to convert surrounding vibrational energy to electricity.

Outlier Detection of Light Buoy Telemetry and Telecontrol Data Based on Improved Adaptive ε Neighborhood DBSCAN Clustering

In this paper, according to the water area of light buoy, the migration rule of light buoy in main channel is counted, and the frequency of light buoy passing through a certain position point in the process of migration is calculated, and the model is verified by buoy position data. An anomaly detection algorithm based on improved adaptive DBSCAN clustering is designed. The size of the ε neighborhood is adaptive according to the wind speed, wave height, and drift distance span of the water area where the light buoy is located. The experimental results show that the improved adaptive DBSCAN clustering algorithm can solve the problem that the common DBSCAN clustering algorithm takes the “hot” water area of the light buoy position or the most likely area in the light buoy migration process as the noise point.

Estimation of the Motion Performance of a Light Buoy Adopting Ecofriendly and Lightweight Materials in Waves

In this study, the methods and results of numerical simulations to estimate the motion performance of a newly developed lightweight light buoy in waves and to check the effect of conceptually developed appendages on that performance were introduced. The results from a potential-based motion analysis with viscous damping coefficients obtained from free decay tests using computational fluid dynamics (CFD) and those obtained from wave motion simulation using CFD were compared. From these results, it was confirmed that viscous damping should be considered when the frequency of an incoming wave is close to the natural frequency of the buoy. It was estimated that the pitch and heave motions of the light buoy became smaller when the developed appendages were adopted. Although the quantitative superiority of the appendages was different, the qualitative superiority was similar between both results.

A Study on the Development of the Collision Prevention System for Aids to Navigation by Early Identification of the Tug Boat

Aid to navigation is a navigational aid facility that informs a sailing vessel of its location and direction as well as a location of a specific obstacle by means of a light, shape, color, sound, radio wave, etc. It can be valuable in improving the safety of day and night vessel navigation at sea. For the safety of the tug boat, the minimum equipment requirements for each type of tug boat are arranged. Despite these preparations, the collision accidents between tug boats, barges, and light buoys can occur when the tug boat turns due to the length of the tow-line, tidal current, and the barge’s momentum etc. The purpose of this study was to propose the basic system that analyzes the physical relationship between two vessels regarding the tug boat-barge-light buoy dynamics and propagate the corresponding data through the aid to navigation management & operation systems in use at each regional oceans and fisheries.

Motion Analysis of Light Buoys Combined with 7 Nautical Mile Self-Contained Lantern

Motion Analysis of Light Buoys Combined with 7 Nautical Mile Self-Contained Lantern

Towards wide-swath high-resolution mapping of total ocean surface current vectors from space: Airborne proof-of-concept and validation

Two-dimensional high-resolution maps of total surface current vectors obtained for the first time with an airborne demonstrator of the innovative Wavemill instrument concept are validated against HF radar data and compared with output from the POLCOMS high-resolution coastal ocean circulation model. Wavemill is a squinted along-track interferometric SAR system optimized for ocean surface current vector retrieval that operates at moderate incidence angles (∼30°) and is compatible with spaceborne implementation. This paper represents the first comprehensive validation of the current retrieval capabilities of squinted along-track SAR interferometry in support of its development as a future European Space Agency Earth Explorer mission.Wavemill airborne data were acquired in October 2011 in Liverpool Bay off the west coast of Great Britain in light southerly wind (5.5m/s) and maximum tidal ebbing flow (0.7m/s) conditions. Contributions to the measured SAR interferometric phase by surface gravity waves, known as the Wind-wave induced Artefact Surface Velocity (WASV), were removed using our best estimate of wind conditions and the (Mouche et al., 2012) empirical correction derived from Envisat ASAR. Validation of the 1.5km resolution Wavemill current vectors against independent current measurements from HF radar gives very encouraging results, with Wavemill biases and precisions typically better than 0.05m/s and 0.1m/s for surface current speed, and better than 10° and 7° for current direction.The sensitivity of the current retrieval to the wind vector used to compute the WASV is estimated. A ± 1m/s error (bias) in wind speed has minimal impact on the quality of the retrieved currents. In contrast, the choice of wind direction is critical: a bias of ± 15° in the direction of the wind vector degrades the accuracy of the airborne current speed against the HF radar by about ± 0.2m/s. This highlights the need for future instruments to provide calibrated SAR Normalised Radar Cross Section data to support retrieval of wind and current vectors simultaneously.Comparisons of POLCOMS surface currents with HF radar data indicate that the model reproduces well the overall temporal evolution of the tidal current (correlation of spatial fields against HF radar over two tidal cycles of 0.9) but that the model features a systematic 1-h delay in the timing of the maximum ebbing flow in eastern parts of the domain near the Mersey Bar Light buoy. At the maximum ebb flow, the model underestimates the current speed (bias of −0.2m/s) with respect to the HF radar and Wavemill data at the time of the flights. Both the HF radar and Wavemill data reflect much greater snapshot spatial variability of the ocean surface current field than is present in the model, resulting in poor correlation of instantaneous spatial fields (< 0.5) between POLCOMS and the HF radar data. The Wavemill data reveal high spatial variability of ocean surface currents at fine scales, which are not visible in the 4km resolution HF radar data. Wavemill detects several strong (1–1.5m/s) localized current jets associated with deeper bathymetry channels in shallow waters (< 10 m) that are too narrow or too close to land to be observed by the HF radar. The study confirms the value of synoptic wide-swath maps of high-resolution ocean surface current vectors for coastal applications and to validate and develop high-resolution ocean circulation models.

Paint Delamination Inspection for Light Buoys by Infrared Thermography with Distance Heating

Paint Delamination Inspection for Light Buoys by Infrared Thermography with Distance Heating

Design of Korean Standard Modular Buoy Body Using Polyethylene Polymer Material for Ship Safety

Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.

해상 브이용 움직임 감시 시스템

해상 브이는 해상 기상상태에 따라 운동 특성이 변한다. 브이의 운동특성은 브이에 설치된 안테나, 전력공급용 태양광 발전시스템 등의 성능에도 영향을 미친다. 그러므로 브이의 운동특성을 파악하여 브이 관리 및 상태 확인에 활용하는 것은 중요하다. 브이 움직임 감시 시스템은 자이로 센서를 이용하여 등부표의 운동 상태를 측정하며 측정된 값은 신호처리 알고리즘에 따라 육상의 PC에 전송한다. 본 연구에서는 움직임 감시 시스템을 적용하여 해상용 브이의 상태를 체계적으로 감시 및 관리 메카니즘을 구축하고자 하는 것이 연구의 목적이다. 본 논문에서 설계한 브이용 움직임 감시시스템은 향후 브이의 상태를 실시간으로 파악하거나 해상구조물의 움직임을 예측하는 연구 분야 등에 적용 유용하게 사용될 것이다. Buoy has different motion characteristics depends on the sea weather situations. The motion characteristics has an impact on antenna, solar power generation system and etc. installed within a buoy. Therefore, it is important to analyse motion characteristics for management and analyse the buoy conditions. This paper's Buoy motion monitoring system uses gyro sensor to detect motions of a light buoy, and the measured data transfers to the PC on the shore using signal processing algorithm. The aim of this research is to develop monitoring and management mechanism of a buoy by applying motion monitoring system. In this paper, the operation characteristic of movement monitoring system is verified through experiment. Further, in this paper, it can apply such as real-time visibility into the status of the buoy or many ocean facility's motion estimation of the future.

국내 무역항 항로의 등부표 시인거리와 배치에 관한 이용자 분석

본 논문에서는 국내 무역항 항로에 배치되는 등부표의 최적 배치에 대한 기준을 설정하기 위한 기초자료로서 항해자들을 대상으로 등부표의 시인거리와 배치에 대한 선호를 분석하였다. 무역항의 각 규모를 감안하여 항만별로 약 <TEX>$30{\sim}150$</TEX>부의 설문지를 배포하였고, 총 356부의 유효한 설문지가 분석에 사용되었다. 육안으로 청명한 날씨의 주간에 부표를 인지하는 거리는 <TEX>$2{\sim}4$</TEX>마일이 55.0%로 가장 많았다. 부표의 배치방식에서는 양측 부표방식의 선호가 62.1%로써 가장 높았다 또한 부표의 전후사이의 선호 간격은 평균 1.09마일이었다 쌍안경 없이 시인할 수 있는 부표의 기수는 2기가 40.6%로 가장 선호되었다. This paper analyzed the visual range and arrangement of light buoy on navigation officers as the primary material to establish the standard of optimal arrangement of light buoy on the channel of the domestic trade-port. About <TEX>$30{\sim}150$</TEX> questionnaires by port were distributed according to the scale of trade-ports and then Effective total 356 copies were used in analysis. The distance, <TEX>$2{\sim}4$</TEX>mile, occupied the highest percentage 55.0% as the visual range with naked eyes at the daytime in bright weather. At the arrangement way of light buoy the both sides buoy method showed high in the preference 62.1% among the respondents. The preferred interval between sequence buoys was averagely 1.09mile. Also, the preferred number of light buoy was two in the preference 40.6% among them to cognize without binoculars.

Research into The Future Development of the Hybrid System for Buoy

This paper reports the performance of a 150W PV-wave hybrid system with battery storage in buoy. This system was originally designed to meet a new hybrid power system for buoy in Korea. In the case of lighted buoys and lighthouses, a light failure alarm system of wireless radio is attached so that light failures are immediately notified to the office. At lighthouse offshore fixed lights and light buoys where commercial electricity is not available, the power source depends on solar system and batteries. This power system has a various problems. Therefore energy derived from the sunshine, wind and waves has been used as the energy source for aids to navigation. Recently a hybrid system of combining the solar, wind and the wave generator is a favorable system for the ocean facilities like lighthouse and buoy. The hybrid system in this paper is intended for variable DC load like light, communication system in the buoy and includes a PV-wave generation system and battery. This is composed a high efficiency charging algorithm, switching converter and controller. This paper includes discussion on system reliability, power quality, and effects of hybrid system in the buoy. Simulation and experimental results show excellent performance.

単独測位方式によるＧＰＳ波浪観測システムの実証実験

Ocean wave information is indispensable for a coastal activity and service of ship to be carried out safely and economically. A low-cost wave height and direction sensor was developed by Japan Aerospace Exploration Agency and Japan Weather Association. The purpose of this study is to examine observation accuracy of wave height, period, and direction on the light buoy of Japan Coast Guard. Then, we installed a low-cost wave height and direction sensor on the light buoy and observed ocean wave in the sea. And, we compared data observed by light buoy with data observed by NOWPHAS (Nationwide Ocean Wave information network for Port and HArbourS). Our results show that observation accuracy on the light buoy is high.

A Study on the Collision Accident between Ferry Golden Jindo and Ferry Princess

Ferry Golden Jindo collided with Ferry Princess near the No.7 light buoy of Incheon Port No.1 Passage in restricted visibility due to dense fog. The result was that Ferry Golden Jindo got a hole at the starboard midship section shell plating and Ferry Princess sustained damages at the starboard bow and 25 persons injured The aim of this paper is to investigate this collision accident, to clarify its causes, and to prevent such accident from occurring again In short, this collision resulted from Princess' high speed in restricted visibility, Golden Jindo's carelessness of watchkeeping, lack of proper safety training of crew, lack of instruction of supervisor, carelessness af PTMS Center and indifference of Korea Shipping Association, etc.

105 操船シミュレータ上の航路標識灯火の表現手法

We have aimed to improve safety of ship navigation at night and studied appropriate passage routes on ship handling simulator taking Kanmon Passage as an example.As we enhance recognition of the passage route, we prepared several ways such as changing character of light buoys or corresponding/cascading buoys lighting. We have represented lights of aids to navigation such as buoys and lighthouses accurately in our ship handling simulator and executed simulator experiments to test those ways. To represent accurate representation of lights, we have made several CGI objects based on their colors, their luminosity and luminance of CGI on screen. A buoy chooses appropriate object automatically from them according to its own luminosity and a distance between the buoy and a viewpoint. Besides we have added equations of atmospheric transmittance to our program and realized visibility of light on our simulator. We discuss those methods in this paper.