Study On Ship Form Evaluate Alternatives And Intelligent Decision-Making Methods

The process of ship form evaluate alternatives is a multiple criteria and multiple objectives one, which is mainly based on the designers' subjective experience in the past. The bias error is inevitable because the result mainly depends on the designers' subjectivity. With the development of modern science and technology, the decision-making theories and methods, which based on the AI are developing fast and applied in all kinds of fields. In the field of ship engineering, the study about systematic optimization and intelligent decision-making is coming into being and obtains great achievements. The appearance of DSS in the age of 1970 pushes the decision-making theories into a new developing peak and becomes a new computer-based information systems management tool in the field of systems engineering, management science and AI, which is always used to tackle semi-structural and non-structural information systems decision-making problem. In the early age of 1990, the appearance of new decision-making technology, that is the OLAP and DW which based on the DM, supplements many new functions such as data cleaning, abstraction, transforming and analysis and so on, embodies its predominance when faces the massive data and at the same time, orientates the future development of the decision-making theories and methods.The process of setting up the ship form main dimensions is mainly relied on the multivariate and stepwise regression in the past which based on the massive subsistent data including the main dimensions, Light Weight, storage capacity, stability and total cost and so on. With the appearance of the technology of ANN and AI, the BP network is used predicting and simulating in all kinds of fields. But it has intrinsic defects such as low convergence and local minimum because the negative gradient method is adopted in weight adjusting. An improved RBF network is introduced which has the advantage in digital approximation, classification and learning rate and at the same time, the corresponding sensibility is also analysed.The traditional MCDM, which named grid method, picks out the best one from many ship form alternatives through synthetical engineering economic analysis after making multiple objectives evaluation. It is very obvious that the ultimate result is mainly decided by the designers' subjectivity and lacksscientificalness and rationality. The AHP method can make full use of subjective initiative besides that sometimes designers can not distinguish the relative importance between indices each other. An improved AHP method is offered which simplified the judgement matrix in order to enhance the precision of weight. At the same time, a new decision-making method which determines the indices weight on the basis of the subjective preference and objective information entropy with the strict Least Square Method as a tool is provided in the process of MCDM.With the development of worldwide shipping market, all kinds of special ship types and corresponding ship form evaluate alternatives are emerging. The traditional (GB11697-89) method is only suitable for common ship types and it is not suitable for ocean floating structure system evaluation either. It is demoded that making techno-economic verification with the traditional GB. Two special ship types, that are car carrier and FPSO, are introduced including main dimensions, design feature and the corresponding engineering economic analysis is made on the basis of GB. It is tested that the innovatory system of indices can not only reflect the characteristic of special ship types but also enrich the original GB system and at the same time, put forward a new groping field for the ship designers.The AI technology is developing fast and the related decision-making ideology is applied in all sorts of fields. A set of IDSS-SPD system info model used in the ship preliminary design is offered and at the same time, the modern AI technology, such as DW, OLAP and DM is also provided and syncretized into the traditional DSS in order to aid the ship desi...