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Estimation of changes in marine traffic flow due to installation of virtual buoys based on the OZT method

Fukuda G., Tamaru H., Shoji R.

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

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2021

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Vol. 15 No. 2

445--454

EN

In this study, changes in maritime traffic flow due to the installation of virtual buoys were analysed from the perspective of collision, based on the obstacle zone by target (OZT) method. The existence of an OZT within ±2° in the bow direction is considered to be dangerous; all the OZTs that a vessel encountered at the time when this orientation prevailed were subjected to analysis. For the calculation of the OZT model, an SD3 model was used. The estimated OZT was used to calculate the OZT density, and the positions of the ships that were encountering the OZT were used for the analysis. It was found that the OZT density at the locations where collisions had occurred in the past was approximately 0.01 [times/km2]. After the installation of virtual buoys, most places around there were reduced to around approximately 0.005 [times/km2]. The results imply that the installation of virtual buoys has reduced the risk of collisions. In contrast, the OZT density in the southern region of Buoy 1 increased from approximately 0.005 [times/km2] to approximately 0.01 [times/km2], suggesting that a more detailed analysis of this area is required.

2

Development of analytical method for finding the high risk collision areas

Fukuda G., Shoji R.

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

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2017

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Vol. 11, no. 3

531--536

EN

The traffic condition has been analyzed by models that are based on Gas model and Obstacle Zone by Target (OZT) by using 1 year AIS data for Tsunami measure. By applying Gas model based method, it is possible to analyze the area in terms of ships' relative angle, size, speed and density. The OZT is originally developed to show the collision zone on the target ship's course. By using this method to the marine traffic analysis, high possibility of collision areas are estimated. Moreover, ships that courses are heading to OZT are identified and studied their position and how long they proceed course heading to OZT.

3

On the Fuel Saving Operation for Coastal Merchant Ships using Weather Routing

Takashima K., Mezaoui B., Shoji R.

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

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2009

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Vol. 3, no. 4

401--406

EN

It is well known that Weather Routing is one of the effective ship operation methods to reduce fuel consumption and many studies have been conducted to develop the effective calculation methods. However, most studies were performed focusing on the ocean going ships, and there were few studies made for coastal ships. The authors propose a minimum fuel route calculation method for coastal ships that use the precise forecasted environmental data and the propulsion performance data of the ship on actual seas. In the proposed method, we use the Dijkstra’s algorithm to calculate an optimum minimum fuel route suitable for coastal ships. Simulation study was carried out to evaluate the effectiveness of the proposed method using two coastal ships. As the result of study, the authors confirmed that the proposed calculation method is effective for fuel consumption reduction and is applicable for the operation of coastal merchant ships.

4

Surface durability of steel rollers lubricated by fresh and used engine oils in comparison with gear oil

Ishibashi A., Sonoda K., Sunagawa Y., Shoji R.

International Journal of Applied Mechanics and Engineering

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2004

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Vol. 9, no spec.

79-85

EN

The lubricating oil used for the gasoline engine of passenger cars has been exchanged for a fresh oil after running a distance in the range of 3.000 to 10.000km, in Japan, in most cases. In the present investigation, used engine-oils were obtained by two different methods; (1) the oils were gathered at a car service centre, or (2) produced using test cars and fresh engine oils. The fresh and used engine-oils were chemically analysed and the amounts of nine elements (S, Cl, P, Zn, Pb, Mo, Fe, Al, Ca) in the oils were compared with those of a gear lubricating oil. Using a four ball tester, scoring load for the test oils were measured and then surface durability tests were conducted using a two roller testing machine. Many pits occurred at a Hertzian contact pressure of 1.000MPa on the steel rollers with a hardness of 180HB when a fresh engine-oil or the gear oil was used for lubricating the rollers. However, not a single pit occurred at the same contact pressure up to 10 million rotations when the used engine-oil was used. The reason for the higher surface durability was explained using the results of the chemical analyses and scoring tests.