Real-time Ship Research Articles

Development of a quantitative risk assessment model for ship collisions in fairways

This study develops a quantitative risk assessment (QRA) model to evaluate the risk of ship being involved in ship collisions which takes into account the frequency and consequence of all possible accident scenarios. Two accident consequence types including human life loss and oil pollution which is measured in terms of the volume of oil spilled are considered in this study. The proposed QRA model consists of a collision frequency estimation model, an event tree and consequence estimation models. The event tree comprises five intermediate events including ship type, ship size, loading condition, hull damage and survivability. Two “generic” mathematic models are developed to estimate the human life loss and oil pollution caused by ship collisions, respectively. A case study is finally created using the real-time ship movement data in the Singapore Strait from the Llyod’s Marine Intelligence Unit (Lloyd’s MIU) database. Results show that the container ship, bulk carrier and oil tanker are the three main ship types being involved in collision accidents. Although the passenger/RORO ship has the lowest frequency being involved in collisions, it will suffer the most serious consequence in terms of the human life loss once it is involved in an accident. Considering the relative high percentage of oil tankers involving in ship collisions and their severe consequences, focus should be placed on the tracking and management of oil tanker traffic.

천리안 위성통신을 이용한 실시간 원격 선박 모니터링 체계 구축

천리안 위성통신을 이용한 실시간 원격 선박 모니터링 체계 구축

CFD simulation of wind flow over natural complex terrain: Case study with validation by field measurements for Ria de Ferrol, Galicia, Spain

Accurate and reliable Computational Fluid Dynamics (CFD) simulations of wind flow over natural complex terrain are important for a wide range of applications including dispersion of pollutants, wind energy resource assessment and ship manoeuvring in channels and near harbours. In the past 50 years, a very large number of CFD studies of wind flow over hills have been performed. However, a detailed review of the literature shows a lack of CFD studies including validation by field measurements for natural complex terrain beyond the case of isolated hills. Therefore, this paper presents a CFD study with field measurement validation for natural complex terrain that consists of an irregular succession of hills and valleys surrounding a narrow entrance channel. The aim of the study is twofold: (1) to evaluate the accuracy of 3D steady Reynolds-averaged Navier–Stokes (RANS) simulations with a revised k–ε model for calculating mean wind-velocity patterns over this type of natural complex terrain; and (2) to provide mean velocity data that can be used as input for real-time ship manoeuvring simulations to evaluate accessing the LNG terminal with larger LNG carriers. The irregular hilly terrain is expected to yield complex wind environmental conditions in the channel and complex forces on the LNG carriers. The study focuses on high wind speed conditions, for which the atmospheric boundary layer exhibits neutral stratification. The simulations are performed with 3D steady RANS and the realisable k–ε model for 12 wind directions. Special attention is given to surface roughness parameterisation and specification. The simulation results of mean wind speed and wind direction are generally within 10–20% of the corresponding measurement values. The results show that for wind directions 60° and 90°, the funnelling effect leads to an increase of wind speed in the channel compared to the wind speed over open sea. For other wind directions, the topography leads to a reduction of the wind speed in the channel, but also to strong wind speed gradients along the channel axis, which are important for ship manoeuvring. The study shows that for the present application, the 3D steady RANS approach with the realisable k–ε model can provide an accurate assessment of the complex mean wind-flow patterns and the funnelling effect by the natural complex topography on the wind.

Hull deformation measurement for spacecraft TT&C ship by Photogrammetry

When voyaging, ships are subject to inevitable hull deformations caused by the changes in the environmental temperature and external stress. These are a crucial source of errors when measuring data using a spacecraft tracking, telemetry, and control (TT&C) ship. A prototype system based on photogrammetry was developed for the real-time measurement of a spacecraft TT&C ship’s hull deformation. This system has high accuracy, a simple structure, and convenient maintenance, and requires few changes to the ship’s structures. To improve its performance, an estimation approach is proposed for hull deformation angles. With the proposed approach, the central positions of cross spots in successive frames can be predicted based on the prediction of the camera’s attitude, and their extract locations can be found by defining a series of small windows around each predictive location. Then, the optimal estimate of the camera’s attitude is updated by the designed extended Kalman filter using the extracted cross spots and their corresponding local coordinates, with which the hull deformation angles can be found. To verify the proposed measurement approach, its performance was tested during the normal sailing, floating, and rocking on the sea of a spacecraft TT&C ship. The experimental testing results demonstrated that the proposed approach performs well in terms of accuracy and robustness. It can satisfy the hull deformation measurement requirement for a spacecraft TT&C ship in real time.

SAN 환경에서 클러스터 기반의 멀티채널 알고리즘

Ship Area Network(SAN) can monitor the status of ship in real time and minimize the maintenance costs by connecting various devices to the network. In particular, among researches on SAN, Wireless Sensor Network using sensor nodes that is low-cost, low-power, and multifunctional has a number of advantages. In this paper, we propose cluster-based multi-channel algorithm considering the energy efficiency in wireless sensor network in a ship. The proposed algorithm shows the result of improvement of throughput and energy efficiency, because it reduces interference between clusters by using channel allocation algorithm that is distributed and dynamic.

Interactive 3D desktop ship simulator for testing and training offloading manoeuvres

The paper presents a software system for interactive 3D simulations of offloading operations commonly executed in offshore scenarios. The system was developed to simulate an LNG vessel approaching or departing from a FPSO unit or LNG tanker in 3D Virtual Environment. However, it has the capabilities of a global purpose manoeuvring simulator, including state of the art models of manoeuvrability, sea-keeping and sea surface simulations, which are integrated into the system. Additionally to common real-time physically based manoeuvrability simulators, this simulator also includes real-time ship motions calculations. The system architecture is composed of three main modules that support interaction and real-time data exchange with the integrated mathematical models. The manoeuvrability module allows the user to control the steering gear, the main engine and the bow thrusters, through the Virtual Environment. The seakeeping module computes wave induced ship motions in real-time according to ship's position, heading and speed, based on pre-calculated response amplitude operators. The sea surface module generates and simulates sea states defined by wave spectra. The system takes advantage of the programmable capabilities of the graphics processor units to increase the performance and realism of the simulations. The simulator may be used by operation planners and ship masters, as a tool for testing and training different offloading scenarios and approaching manoeuvres.

Technology of Information Collection and Analysis about Steering Operation Behavior of Inland Waterway Sailing Ship

ABSTRACT He, H.; Xiong, J.; Liu, M.; Chu, X.; Liu, C.; Shi, L., and Wang, L., 2015. Technology of information collection and analysis about steering operation behavior of inland waterway sailing ship. Steering operation behavior is an important factor which affects the safety of ship navigation. This article used suitable method of information acquisition and information transmission and analyzed key technologies of steering behavior data collection, transmission and display, and then developed a monitoring system software for inland waterway ship sailing condition. This software is capable of tracking the ship in real time, displaying the static and dynamic information, operation information and environment information, as well as querying the historical trend functions. After the application, it shows that the software can display real-time steering operation behavior and realize remote management.

Ship Collision Frequency Estimation in Port Fairways: A Case Study

This study aims to evaluate ship collision frequency in port fairways. One case study is created using one month's real-time ship movement data from five major Singapore port fairways. Results show that tankers account for the biggest proportion in the Temasek fairway, whereas the percentage of Roll-on-Roll-Off (RORO) and passenger ships is quite small in the Temasek fairway, Sinki fairway, Jong fairway and Southern fairway. Tankers and container ships are the two major ship types involved in dangerous encounters. The largest number of dangerous head-on and overtaking encounters is located in the Jong fairway. The majority of dangerous crossing encounters have occurred in the West Keppel fairway and Jong fairway. Ship collision frequency at night is found to be significantly higher than during the day in these fairways.

Automated Map Generation for the Physical Traveling Salesman Problem

This paper presents a method for generating complex problems that allow multiple nonobvious solutions for the physical traveling salesman problem (PTSP). PTSP is a single-player game adaptation of the classical traveling salesman problem that makes use of a simple physics model: the player has to visit a number of waypoints as quickly as possible by navigating a ship in real time across an obstacle-filled 2-D map. The difficulty of this game depends on the distribution of waypoints and obstacles across the 2-D plane. Due to the physics of the game, the shortest route is not necessarily the fastest, as the ship's momentum makes it difficult to turn sharply at high speed. This paper proposes an evolutionary approach to obtaining maps where the optimal solution is not immediately obvious. In particular, any optimal route for these maps should differ distinctively from: 1) the optimal distance-based TSP route and 2) the route that corresponds to always approaching the nearest waypoint first. To achieve this, the evolutionary algorithm covariance matrix adaptation-evolutionary strategy (CMA-ES) is employed, where maps, indirectly represented as vectors of real numbers, are evolved to differentiate maximally between a game-playing agent that follows two or more different routes. The results presented in this paper show that CMA-ES is able to generate maps that fulfil the desired conditions.

Adaptive Real-Time Ship Detection and Tracking Using Morphological Operations

In this paper, we propose an algorithm that can efficiently detect and monitor multiple ships in real-time. The proposed algorithm uses morphological operations and edge information for detecting and tracking ships. We used smoothing filter with a <TEX>$3{\times}3$</TEX> Gaussian window and luminance component instead of RGB components in the captured image. Additionally, we applied Sobel operator for edge detection and a threshold for binary images. Finally, object labeling with connectivity and morphological operation with open and erosion were used for ship detection. Compared with conventional methods, the proposed method is meant to be used mainly in coastal surveillance systems and monitoring systems of harbors. A system based on this method was tested for both stationary and non-stationary backgrounds, and the results of the detection and tracking rates were more than 97% on average. Thousands of image frames and 20 different video sequences in both online and offline modes were tested, and an overall detection rate of 97.6% was achieved.

A fast line-scanning-based detection algorithm for real-time SAR ship detection

Synthetic aperture radar (SAR) provides a powerful surveillance capability allowing the observation of target, independently from weather effects and from the day and night cycle. Unfortunately, the automatic interpretation of SAR images is often complicated and time consuming. In support of real-time vessel monitoring, a fast line-scanning detector designed for detecting ships from SAR imagery is proposed in this paper. The detector does not require any prior knowledge about ships and background observation. It uses a novel local gray-level gathering degree algorithm to detect potential targets and then a complementary filtering scheme to reject false alarms. The performance analysis over real SAR images confirms that the proposed detector works well in various circumstances with high detection rate, fast detection speed and perfect shape preservation.

Real-Time Ship Motion Prediction Based on Time Delay Wavelet Neural Network

A wavelet neural network with time delay is proposed based on nonlinear autoregressive model with exogenous inputs (NARMAX) model, and the sensitivity method is applied in the selection of network inputs. The inclusion of delayed system information improves the network’s capability of representing the dynamic changes of time-varying systems. The implement of sensitivity analysis reduces the dimension of input as well as the dimension of networks, thus improving its generalization ability. The time delay wavelet neural network was implemented to real-time ship motion prediction, simulations are conducted based on the measured data of vessel “YUKUN,” and the results demonstrate that the feasibility of the proposed method.

선박관리 시스템의 최적화

In this paper, an effort has been made to design and develop an optimized programming model for Real-time Ship Management System. Replacing the conventional interrupt-driven programming model, an embedded real-time operating system (RTOS) has been implemented on the system, allowing processes to run virtually simultaneous and multitasking. Data management algorithms are designed and developed in the RTOS to facilitate data distribution amongst tasks and optimize the CPU processing time through intelligent resource utilization. Finally, data lost in the system has been minimized via the improvement of data processing rate under the optimized programming model.

Multi sensor intelligent data fusion algorithm for principal component analysis

By combining Neural Networks (NN) with Principal Component Analysis (PCA), an algorithm for Multi-Sensor Intelligent Data Fusion (MSIDF) with an effective feature selection method is proposed. When the sensor vector dimension is high, it reduces the dimension by using PCA decomposition to is calculated the simplify data. Then the smallest error rate upper bound is tested by the iterative algorithm of neural networks data fusion. The proposed algorithm in sampling real time ship’s sensor data in experiments and gives a better performance. The proposed method can improve the fusion rate effectively and reduce the PCA computation time. The discussed algorithm is very useful in practice.

Functional Requirements to Support Traffic Organization Service

In the era of e-Navigation, the future Vessel Traffic Services (VTS) is anticipated to play an important role on the enhancement of maritime safety and the efficiency of maritime transport as a key stakeholder of e-Navigation. The VTS services need the advanced Traffic Organization Service (TOS). In this paper, the VTS functions for TOS is revisited from the reports of IMO e-Navigation Correspondence Group and IALA VTS Committee. In Korea, the research activities to enhance the existing VTS functions have been conducted. In terms of TOS, some VTS functions have been developed. In conclusion, all the past traffic data and real-time ship data are required to provide the advanced TOS. For this, the advanced functions to support TOS should be implemented on VTS console.

배경 구축 기법과 형태학적 연산 기반의 다중 선박 객체 검출

선박 객체 검출 기술은 입력된 비디오 및 영상 데이터에서 선박 객체가 존재하는 경우 선박의 위치를 검출하는 기술로서 입력 영상의 환경 변화와 잡음의 영향에 따라서 검출 정확도의 편차가 높다. 이런 문제점을 해결하기 위하여 본 논문에서는 배경 구축 기법과 형태학적 연산 기반의 다중 선박 객체 검출 기술을 제안한다. 제안하는 방법은 배경 제거 단계, 잡음 제거 단계, 객체 기준 위치 설정 단계, 객체 재구성 단계, 다중 객체 검출 단계 등 5단계를 거쳐서 선박을 검출한다. 다양한 변수를 고려한 15가지 실험 비디오를 대상으로 한 실험을 통해서 98.7%의 검출율을 나타내었으며, 환경 변화에 강인한 검출을 수행하는 것을 확인할 수 있었다. 제안하는 방법은 해상 관제와 선박 자동 운항 기술의 기반 기술로서 유용하게 사용될 수 있다. Ship object detection is a technique to detect the existence and the location of ship when ship objects are shown on input image sequence, and there are wide variations in accuracy due to environmental changes and noise of input image. In order to solve this problem, in this paper, we propose multiple ship object detection based on background registration technique and morphology operation. The proposed method consists of the following five steps: background elimination step, noise elimination step, object standard position setting step, object restructure step, and multiple object detection steps. The experimental results show accurate and real-time ship detection for 15 different test sequences with a detection rate of 98.7%, and robustness against variable environment. The proposed method may be helpful as the base technique of sea surface monitoring or automatic ship sailing.

안전한 e-Navigation을 위한 해상교통관제 시스템의 정보교환 보안구조 설계

A concept of the e-Navigation was introduced in 2005 and implementation strategies are under way by IMO/IALA in the maritime safety area. Specially VTS is an important maritime traffic monitoring and aids to navigation system which is aims to improve safety, navigation efficiency and protect the marine environment. The demand of the inter-VTS networking has been increased and standardization is underway for realization of shore side collaboration for maritime safety in IALA. But there may be security problems in the inter-VTS networks if they have not proper security mechanism. The hacking of realtime ship position and sensitive maritime surveillance information caused a critical accident of vessel, human life and environment by terrorist. This paper aims to design of a secure inter-VTS network structure and related security protocol for secure sharing of sensitive maritime data.

Ship collision risk assessment for the Singapore Strait

The Singapore Strait is considered as the bottleneck and chokepoint of the shipping routes connecting the Indian and the Pacific Ocean. Therefore, the ship collision risk assessment is of significant importance for ships passing through the narrow, shallow, and busy waterway. In this paper, three ship collision risk indices are initially proposed to quantitatively assess the ship collision risks in the Strait: index of speed dispersion, degree of acceleration and deceleration, and number of fuzzy ship domain overlaps. These three risk indices for the Singapore Strait are estimated by using the real-time ship locations and sailing speeds provide by Lloyd's MIU automatic identification system (AIS). Based on estimation of these three risk indices, it can be concluded that Legs 4W, 5W, 11E, and 12E are the most risky legs in the Strait. Therefore, the ship collision risk reduction solutions should be prioritized being implemented in these four legs. This study also finds that around 25% of the vessels sail with a speed in excess of the speed limit, which results in higher potentials of ship collision. Analysis indicates that the safety level would be significantly improved if all the vessels follow the passage guidelines.

Ship Motion and Wave Radar Data Fusion for Shipboard Wave Measurement

Defence Research and Development Canada (DRDC) Atlantic has conducted many dedicated seakeeping and structural load trials on the Canadian Navy research ship CFAV Quest and on several Canadian Navy warships. Typically, wave buoys have been deployed to measure seaway wave characteristics; however, there has been an ongoing interest in evaluating shipboard wave measurement systems. These systems have some advantages over wave buoys for short-term trials and are needed for longer-term sea trials and to provide wave input data for tactical and real-time ship operator guidance systems. This paper presents some of our experiences with wave radar. In the last few years there have been significant advances in wave radar technology (systems that extract wave data from backscatter information contained in the video output of X-band navigational radar displays). Commercial "off-the-shelf" systems are now available. While there is evidence that these systems can provide reliable wave data from shore-based or stationary platform installations, it is DRDC's experience on a ship moving in waves, that wave radars can give good direction and frequency measurements but less reliable wave heights. DRDC has developed a method to improve shipboard wave height measurement through fusion of wave radar data with measured ship motion response data. This paper discusses the development of the wave data fusion process, validated through previous sea trial data, and presents the results of a recent demonstration of the approach during a sea trial conducted on CFAV Quest in November/December 2008.

Robust real-time ship detection and tracking for visual surveillance of cage aquaculture

This paper presents a visual surveillance scheme for cage aquaculture that automatically detects and tracks ships (intruders). For ship detection and tracking, we propose a robust foreground detection and background updating to effectively reduce the influence of sea waves. Furthermore, we propose a fast 4-connected component labeling method to greatly reduce the computational cost associated with the conventional method. Wave ripples are removed from regions with ships. An improved full search algorithm based on adaptive template block matching with a wave ripple removal is presented to quickly, accurately, and reliably track overlapping ships whose scales change. Experimental results demonstrate that the proposed schemes have outstanding performance in ship detection and tracking. The proposed visual surveillance system for cage aquaculture triggers an alarm if intruders are detected. The security of cage aquaculture can be increased. The proposed visual surveillance can thus greatly help the popularization of cage aquaculture for ocean farming.