Kuniji Kose

A simulation-based procedure for expert system evaluation

It is well recognized that the evaluation of the knowledge-based system is very important and difficult in the development of expert systems in the domains such as aviation and navigation. To alleviate some of the difficulties, and to reduce the development cost, the authors proposed an evaluating procedure based on simulation. The proposed procedure was designed to validate the functionality and capability of an expert system that was developed to provide decision-making support in ship navigation. In this paper, the developed expert system for collision avoidance is first outlined, and the procedure to evaluate the developed expert system by using a simulation-based approach is presented in details. It is also concluded that the simulation-based procedure is feasible and effective for evaluating expert systems in a number of different domains.

A New Collision-Avoidance-Supporting-System and Its Application to Coastal-Cargo-Ship "Shoyo Maru"

Abstract Authors developed the collision avoidance supporting system based on a new concept to carry out “Strategic Maneuvering”. The system was installed in the coastal cargo ship and some problem concerned with availability of the system were obtained during demonstrative experiments. Authors identified several problem with adjustment system’s indication to user feeling and tuned it suitable. As a result, it was confirmed that system support was effective for “Strategic Maneuvering”.

Application of KGPS for Ship Trial

Abstract Kinematic GPS(KGPS) can measure a position with high accuracy. By using of more than three GPS antennas, six Degree Of Freedom motion at any points can be calculated. From experiment data, it is shown that the position at center of gravity can be measured excluding rolling motion. Next the effects of KGPS accuracy and ship distortion to rolling motion measurement. Lastly the example of calculation of hydrodynamic coefficients is shown.

On Unusual Phenomenon in Manoeuvrability and its Successful Countermeasure of a Fishery Research Vessel

These days we sometimes have experienced or heard of full-bodied ships with so-called “unusual phenomena” in manoeuvrability, and the number of those ships seems to increase rapidly owing to the growing fullness of ships.Herewith in this paper an example of such a phenomenon appeared in a fishery research vessel is dealt. Turning tests and zig-zag tests were held, using both the ship and the 1/10 scale model. Oblique towing tests, β-varying tests (changing drift angle gradually) and observation of the stern flow, furthermore, were held in a towing tank using the model.Those experiments certify the existence of two separate flow fields around the hull and the occurrence of switching the two states. The large clearance above the propeller and the rudder as well as the full stern form permits the flow passing from starboard to port or vice versa through the clearance. By this flow, two types of unsymmetrical flow separation may occur. The alteration of the flow direction through the clearance accompanies the changes in the separation, the flow field and the force acting on the hull.Basic characteristics of the “unusual phenomena” observed both in the ship and the model can be explained by the unsymmetrical separation and its alteration. The apparent difference between the ship and the model can be also treated by the conception of “switching line”. The “switching line” is defined as the critical state of motion at which the alternation of the flow occurs.In consideration of those experiments, a center fin shutting the clearance was adapted to both the ship and the model. The results are fully satisfactory. In model tests the unsymmetrical separation is no longer observed. Therefore, the course stability recovers almost completely and the ship can keep the course without any difficulty.