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1

Procedure for Marine Traffic Simulation with AIS Data

Miyake R., Fukuto J., Hasegawa K.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2015

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Vol. 9, no. 1

59--66

EN

It is essential to evaluate safety of marine traffic for the improvement of efficiency and safety of marine traffic. Spread of AIS makes observation of actual marine traffic more easily and faster than before. Besides, description of collision avoidance behaviours of ships are indispensable to simulate a realistic marine traffic. It is important to develop and implement an algorithm of collision avoidance corresponding to a target traffic or target area into the marine traffic simulation because actual actions for collision avoidance depend on circumstances where ships are sailing. The authors developed an automated marine traffic simulation system with AIS data. And in this paper, we proposed a series of systematic procedures for marine traffic simulation including analysing for collision avoidance behaviours using AIS data.

2

Consistently Trained Artificial Neural Network for Automatic Ship Berthing Control

Ahmed Y., Hasegawa K.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2015

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Vol. 9, no. 3

417--426

EN

In this paper, consistently trained Artificial Neural Network controller for automatic ship berthing is discussed. Minimum time course changing manoeuvre is utilised to ensure such consistency and a new concept named ‘virtual window’ is introduced. Such consistent teaching data are then used to train two separate multi-layered feed forward neural networks for command rudder and propeller revolution output. After proper training, several known and unknown conditions are tested to judge the effectiveness of the proposed controller using Monte Carlo simulations. After getting acceptable percentages of success, the trained networks are implemented for the free running experiment system to judge the network’s real time response for Esso Osaka 3-m model ship. The network’s behaviour during such experiments is also investigated for possible effect of initial conditions as well as wind disturbances. Moreover, since the final goal point of the proposed controller is set at some distance from the actual pier to ensure safety, therefore a study on automatic tug assistance is also discussed for the final alignment of the ship with actual pier.

3

Qualitative and Quantitative Analysis of Congested Marine Traffic Environment – An Application Using Marine Traffic Simulation System

Hasegawa K., Yamazaki M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2013

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Vol. 7, no. 2

179--184

EN

Difficulty of sailing is quite subjective matter. It depends on various factors. Using Marine Traffic Simulation System (MTSS) developed by Osaka University this challenging subject is discussed. In this system realistic traffic flow including collision avoidance manoeuvres can be reproduced in a given area. Simulation is done for southward of Tokyo Bay, Strait of Singapore and off‐Shanghai area changing traffic volume from 5 or 50 to 150 or 200% of the present volume. As a result, strong proportional relation between near‐miss ratio and traffic density per hour per sailed area is found, independent on traffic volume, area size and configuration. The quantitative evaluation index of the difficulty of sailing, here called risk rate of the area is defined using thus defined traffic density and near‐miss ratio.

4

Proposal of PFS-R as a modelling tool for complex resource sharing discrete production systems.

Hasegawa K., Miyagi P.E., Takahashi K., Ma L.-Q., Sugisawa M.

Systems Science

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1999

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Vol. 25, nr 1

57-70

EN

Recently, the structures of discrete production systems with shared resources, which offers flexibility in dealing with production of multiple types of parts of products, are getting much more complex. Because of increasing complexity of the systems, the structure of graphical representations such as Petri nets becomes more and more elaborated, considerably decreasing the visual and intuitive understanding of systems, and thus, eliminating the value as an interface between system designers and modeller who are involved in the design procedure. This has been the biggest drawback of actual adoption of Petri nets as a modelling tool for such system control despite facts that their benefits have already been recognized. The authors propose a novel graphical representation "PFS-R" suitable for modelling of complex recourse sharing discrete production systems, e.g., FMSs. The PFS-R is an augmented version of PFS (Production Flow Scheme, previously proposed by authors) based on the correspondence from a set of system resources to a set of production steps in PFS. PFS-R is able to model system structures as well as system behaviour in more simplified and transparent manner than conventional Petri net representations. First, the paper introduces basic elements of PFS-R, and equivalent transformation of PFS-R model to hybrid net and Petri net model, taking into account the net conservativity. Next, we present three examples of discrete production systems to illustrate the effectiveness of PFS-R. In addition, we deduce through an example that the correspondence between resources and production steps in process flows has the three structure, which is effective to evaluete whether or not the object designed has a well-defined structure, i.e. so-called conservativity in the terms of Petri net theory.