International Shipbuilding Progress - Volume 48, issue 3

Authors: Lee, Han-Jin | Rhee, Key Pyo

Article Type: Research Article

Abstract: In this paper, a collision avoidance system is developed using the expert system and action space search. Fuzzy theory is used to reason the degree of collision risk, and the A* search method is used to make an avoidance action plan. The action space searched by the ship is formed in the expert system using the marine traffic rules. Simulation results demonstrate that the collision avoidance system with the expert system takes more reasonable actions than …the system without it. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 3, pp. 197-212, 2001

Authors: Rozbicki, M. | Das, P.K. | Crow, A.

Article Type: Research Article

Abstract: The importance of new technologies for first-principles-based preliminary design is critical in the development of economic growth. The cost content of ships fixed in the design process grows enormously rapidly in the early stages of design; it has been estimated that over three quarters of the cost content of a ship can be fixed in the first few weeks of the design process. It is thus vitally important that preliminary design must be carried out using …rapid, robust, reliable and flexible analysis tools in the context of design methodology. The paper describes a data preparation process and finite element analysis for the longitudinal strength of a ship's hull structure at the preliminary design stage. The methodology presented aims to shorten the process of Finite Element model generation. It can be achieved through the simplification of the model and by increasing automation of the process by development of proper software. Both these methods were examined and applied and useful guidelines and remarks are given for the data preparation of a FE model for a full ship. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 3, pp. 213-225, 2001

Authors: Kuo, H.C. | Wu, L.J.

Article Type: Research Article

Abstract: The line heating process has long been used for plate forming in the building of ships, and has always depended on skilled workers. Since shipbuilding companies need reduction of production costs and an increased use of automation, the line heating process must be improved by performing studies on the temperature of plates. In this paper, which discusses laser line heating of the plates, several methods are proposed to predict the heat flux of the laser source …and the temperature fields of the plates. The inverse method and four different Grey methods are used to compute and compare the heat flux of the laser source with prediction of the error in temperature values of the plate in the line heating process. The linear least-squares method is applied to the laser source by boundary conditions in the inverse method. There are boundary conditions for 16 points obtained by experiment. The results of the inverse method for the laser source are found to be in good agreement with experimental results. For the prediction of the plate temperature at the 16 points, four kinds of Grey methods are used to predict the subsequent data for any of the16 points and to estimate the error for different dimensions. The best of the four methods is the New-Dimension-Zero-First-Term G(1,1) Grey method, resulting in errors under 2%. The other 3 methods are the Same-Dimension G(1,1) Grey method, the Same-Dimension-Zero-First-Term G(1,1) Grey method and the New-Dimension G(1,1) Grey method. Keywords: line heating process, Grey method, inverse method Show more

Citation: International Shipbuilding Progress, vol. 48, no. 3, pp. 227-245, 2001

Authors: Koelman, H.J. | Horváth, I. | Aalbers, A.

Article Type: Research Article

Abstract: This paper proposes a new geometric modeling technique, called hybrid representation (H-rep), for modeling ship hulls. The novelty of H-rep is in the integration of wireframe, surface and solid representation in one common data structure, and in providing topological support to surface modeling as well as an enhanced technique for curve fairing. The primary goal is to achieve topological integrity and generality of the new model. After an introduction into geometric modeling, the authors discuss some …problems of direct application of single-patch B-spline and NURBS surface representations in ship hull design. They claim that even if multi-patch extensions of these techniques are applied, the user may find difficulties in terms of the intuitive and straightforward externalisation of the form of ship hulls as well as of the exact modeling of the shape singularities. H-rep lends itself to a more intuitive and robust ship hull design methodology, and allows designers to follow their conventional line-oriented thinking in designing. The authors demonstrate the advantages of the hybrid representation by two examples of ship hull design. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 3, pp. 247-269, 2001