Liu Xiuwen

Real-time ocean wave in multi-channel marine simulator

We present an adaptive scheme for real-time simulating irregular long crest waves in multi-channel marine simulator. The method restricts computations to the visible part of the ocean surface in each view channel, adapts the geometric resolution to the viewing distance and only considers the visible waves wavelengths. The method allows the user to move over an unbounded ocean following the own-ship, and immersed in a real-time updated photo-realistic ocean environment.We present an adaptive scheme for real-time simulating irregular long crest waves in multi-channel marine simulator. The method restricts computations to the visible part of the ocean surface in each view channel, adapts the geometric resolution to the viewing distance and only considers the visible waves wavelengths. The method allows the user to move over an unbounded ocean following the own-ship, and immersed in a real-time updated photo-realistic ocean environment.

Multi-Level Virtual Reality System for Marine Education and Training

Full Mission Marine Simulator (FMMS) is a fully immersive Visual Reality (VR) System for marine education and training and is valuable and effective for fostering the qualified and competent seafarer. However, many problems, such as limited accessibility, high expenditure, and difficult maintenance etc, limit their pervasive use. Then we developed a partially immersive Desktop Marine Teaching System (DMTS) based FMMS which is low cost and easy to maintenance. Furthermore, one Web-based Marine Training Environment (WMTE) is proposed, which fully combining web technology, high fidelity simulation, and e-learning tools to create a more cost-effective and flexible training environment. In this paper, FMMS, DMTS and WMTE are combined together and supplemented each other to a multi-level VR system in the whole marine training process. Experimental results demonstrated that the multi-level VR system can provide a consistent and more effective medium for improving marine education and training.

A Prototype of Marine Search and Rescue Simulator

There are many of distress vessels in marine to wait for succor. Marine Search and Rescue (SAR) is an important social responsibility and it is very urgent to improve marine SAR ability by peacetime training. However, conventional real ship practical training on the sea is expensive and the training circumstance differs from of real SAR circumstance which is very adverse. This paper brings forward one prototype of Marine SAR simulator (MSARS) which is a very effective, flexible and low cost training method. The MSARS is constructed by reusing the existing shiphandling simulators and adding rescue helicopter simulation unit. Then, Global Maritime Distress Safety System (GMDSS) simulation is integrated into the MSARS. Distress vessel, rescue vessels, rescue helicopter are shared one highly realistic and reliably marine SAR virtual environment through visual and auditory display. It can provide all kinds of marine SAR environments and is effective for all kinds of marine SAR missions training. Further more, anti-pirate drilling also can be implemented in the MSARS.

Design radar signal interface for navigation Radar/ARPA simulator using radar display

Using radar/ARPA simulators for seafarers training is made mandatory by International Maritime Organization (lMO) as early as 1978. This paper presents a new radar simulator using one PC, one radar signal interface and one radar display. PC generates radar echo of any sea area and simulates all kinds of radar echo effects and features. Then the radar signal interface receives the radar echo through PC USB and outputs all kinds of signals to radar display. In the interface, lots of logical circuit is implemented by CPLD, which largely simplifies the design and improves the flexibility. Seafarers can operate the radar display in simulated environment of any sea area in Radar/ARPA Operation training. It provides more flexibility and fidelity and effectively improves the training effect. The result shows that this type of radar simulator meets with the requirements of radar simulator standard completely and has been used in our full mission ship handling simulator successfully.

Oil spill simulation based on multiphase theory

Because of the complexity in oil spill at sea, the traditional oil spill simulation method has been difficult to meet the needs for practical application. In order to simulate the movement of oil spill more accurately, an oil spill model based on multiphase theory is established and verified. Considering the requirement of the calculation efficiency in real time system, the 2D Single Layer Hydrodynamic governing equation is adopted in the tidal current field instead of 3D Hydrodynamic current model. The ADI (Alternating Direction Implicit Method) algorithm is applied in discreting the governing equation. In this paper, the mathematical model of oil spill based on multiphase flow and the equation of two-dimensional tidal wave motion are validated, the results are in good agreement with the literature. Finally, a simulation of oil spill at sea is performed; the simulation results are in good agreement with the satellite images.

Ship motion modeling and simulation in Ship Handling Simulator

For developed irregular waves, wave heights or wave amplitudes are gained using the wave spectrums. Based on the hypothesis of Froude-Krylov, ship shape is predigested box. Wave forces and moments to ship motion can be calculated. They are added in the motion mathematical models, and ship six degrees of freedom mathematical models are given. Using the fourth order Runge - Kutta integration method solves differential equations. The mathematical models are applied to Full Mission Ship Handling Simulator. Six degrees of freedom of the ship: the location, attitude and speed and acceleration are passed to the other modules in the navigation simulator, in order to achieve interaction between human and computer. As an example, a cargo ship that its displacement is ten thousand tons are simulated in three sea states, the time histories of motion are good and the viewing scene is very vivid. The results are shown that the mathematical models can meet the engineering demands.

3D scene transmission for Web-based shiphandling training

In this paper, we describe a powerful 3D scene transmission approach for Web-based shiphandling training. Our optimization algorithm achieves this by selectively transmitting only visible geometric objects of the scene that will maximizing the visual quality rendered at the client, based on a cumulative benefit measure along the predicted viewpoint movement by a Dead Reckoning algorithm and the available network bandwidth. The visual quality of the virtual environment can adapt to the available bandwidth fluctuations and an acceptable shiphandling-training is possible even when bandwidth is low.

Web-based maritime training environment

Marine simulation systems have been introduced in maritime education and training to foster the qualified and competent personnel for working in the maritime industry both afloat and ashore. However, there are many problems with most marine simulation systems today: the long development cycle, the high expenditure, the limited accessibility, the difficult maintenance, and the absence of customization etc. Web-based maritime training environment tries to solve these problems, and still allow very realistic and high-interactive marine simulations, delivered and edited via the Web. This paper presents modeling and system design for a Web-based maritime training environment to facilitate online simulation training from anywhere, anytime.