Optimization Study On Demi-hull Dimensions Of Small Water-plane Area Twin Hull Vessels' EEDI Based On Multi-objective Genetic Algorithm

Energy efficiency design index?EEDI?was established in 2011 by international maritime organization?IMO?to measure CO₂emissions from ships.As for small water-plane area twin hull?SWATH?vessels,no relevant institutions and organizations have clearly stipulated their EEDI specifications,but SWATH ships,with their excellent performance,are increasingly widely applied in the field of marine transportation,and the requirements of IMO on EEDI are increasingly strict.Therefore,it is necessary to study the EEDI of SWATH vessels as follows:Firstly,the thesis has analyzed the background of how EEDI was proposed,the factors that calculating Attained EEDI and Required EEDI should consider.Meanwhile,the fit ship types and trends of EEDI have been studied.Secondly,based on the current ordinary transport ship's EEDI validation and the features of SWATH vessel,the suggested norms of SWATH vessels'EEDI verification have been putted forward and some measures were proposed to improve energy efficiency of energy-intensive SWATH vessels.Then the sensitivity of the EEDI formula was analyzed by single and multiple variables methods.Thirdly,in order to search for energy-saving and efficient dimension of demi-hull in small waterplane area twin hull?SWATH?ship,the thesis takes a typical SWATH cross-sea passenger/car ferry as the research object.From the perspective of multi-objective optimization,the author made a reasonable assumption to parameterize the sub-objective design speed and the gross tonnage respectively according to Admiralty Coefficient and the International Convention on Tonnage Measurement of Ships,so as to convert the energy efficiency design index?EEDI?of the main objective to dimension function.Based on the MATLAB optimization toolbox,the author applied the Multi-Objective Genetic Algorithm?MOGA?to define the constraints according to the resistance,strength,structure and energy efficiency requirements and so on,set the optimization parameters while considering the influence of the hybrid function,and obtained the Pareto solution set of the optimized ship type.Finally,the author discussed the calculation results of multi-objective optimization,and compared with the results of single objective optimization,and analyzed the distribution of sheet size elements in multi-objective optimization scheme.Fourthly,the two subgoals speed and gross tonnage have been unified into a new form of the main goal function by using the weighted combination algorithm,the goal planning algorithm and other optimization methods.Then the original multi-objective problem was transformed into a single objective problem with a unified objective function.By analyzing the results of several algorithm,it has been shown that multi-objective genetic algorithm has good adaptability and can obtain abundant alternative optimization solutions,which is beneficial to the decision makers.The thesis has been proposed the EEDI validation specification of SWATH vessels.Based on sensitivity analysis,the speed has been obtained to have the largest influence on EEDI.The energy efficiency of the mother ship was optimized by multi-objective genetic algorithm,and then the applicability and advantages of MOGA were demonstrated.This paper provides references and suggestions for the future enforcement of SWATH vessels'EEDI.