Application Of Extension Theory To Fairway Safety Assessment

As the port scale increases and vessels become lager and larger, fairway safety assessment is becoming more and more important not only for safe operation of fairways in use but also for feasibility analysis of newly-built ones. Hence the application of extension theory to fairway safety assessment is studied in this paper.The problems existing in navigation safety assessment which are about the determination of weights and verification of the new assessment method, together with the problem existing in extensible evaluation which is about the determination of the joint domain, are put forward according to the analysis of the research status. Firstly, a total of 21 indices and the corresponding classical domain which affect the fairway safety are determined with reference to the related articles. The joint domain of certain indices are determined according to the fairway design standards distinctively. The classical domain, together with joint domain, forms the indices system specific to fairway safety assessment. Then a kind of dynamic weight determination method based on simple dependent function is used to determine the weights of different indices. The traditional dynamic weight model is modified according to theoretical analysis, after which the weights of indices show consistent monotonicity as the sample value varies in and between intervals. The weights determined by the modified model can reflect all unfavorable changes of the sample value in the whole joint domain. Based on the indices system and modified dynamic weight model, a method of applying the extension theory to fairway safety assessment is established. Finally, two sets of fairway design plans for Dayao Wan are brought up, then the fairway safety assessment method based on extension theory is applied to the two sets of plans and verified with marine simulator experiments. The consistency between the assessment results coming from the assessment method and the marine simulator experiments proves the validity of the assessment method based on extension theory established in this paper. The dynamic nature of the modified dynamic weight model is verified by comparing the single index weights of the two sets of fairway design plans.The main tasks done in this paper consist of three aspects. Firstly, the joint domain of certain indices is determined according to theoretical analysis, which provides a method to determine the joint domain. Secondly, the traditional dynamic weight model is modified, after which all unfavorable changes of the sample value in the whole joint domain can be reflected by the dynamic weights. Thirdly, the marine simulator experiment is used to verify the validity of the new safety assessment method, in which the area ratio of the track belt is used as the evaluation criterion. The marine simulator experiment can be regarded as a new approach to verify new navigation safety assessment method.