Study On The Optimal Counter-flooding Scheme Design Of Fishing Vessels

With the rapid development of China's economy and the ever-increasing population,the demand for fishery resources has increased in recent years,resulting in a dramatic increase in the number of fishing vessels.In general,China's fishing equipment technology is relatively backward,and the sinking incidents of fishing vessels caused by environmental and human factors(wind,waves,currents,rocks,collisions,etc.)continue to occur.After the damage of the fishing vessel,how to quickly obtain a reasonable and effective Counter-flood scheme is one of the key issues.The correctness of the righting scheme not only directly determines the performance,such as the floating state,stability,and structural strength of the fishing vessel after it is completed,but also determines the safety of the damaged fishing vessel during the righting.At present,the design of the damaged fishing vessel Counter-flood scheme is based on the fishing vessel loading manual or the fishing vessel stability report,and artificial experience method is used to generate the anti-sedimentation plate map for fishermen's reference.For large fishing vessels with more cabins,due to the large number of righting options,it is difficult to quickly obtain the best Counter-flood scheme using artificial experience.The artificial experience method relies heavily on the designer's richness of experience.For the inexperienced designer,there is a problem that the repeated calculation is heavy,the design speed is slow,and an effective Counter-flood scheme cannot be obtained quickly.The design of the damaged fishing centering scheme is a multi-objective combinatorial optimization problem with multiple nonlinear constraints.When there are many compartments that can be used for righting,the number of possible combinations will explode,and it is not easy to find the optimal solution.In order to solve this problem,this paper starts with the design of a new method to solve the Counter-flood scheme,and studies the method for solving the Counter-flood scheme with fishing vessel characteristics.The research goal is to realize the automatic,rapid and efficient solution to the optimal Counter-flood scheme of damaged fishing vessels under the premise of comprehensive consideration of the safety performance of various performance indicators in the process of correcting the fishing vessel.The main research content and innovations:1)Summarize and analyze the problem of correcting damaged fishing vessels and study the principle of supporting and correcting the fishing vessels.Based on the theory of ship unsinkability,combined with iterative and cumulative ideas,the process of breaking a damaged fishing vessel from the end of damage to the end of righting is divided into accumulation of multiple discharge loads or multiple injections of loads,and detailed calculation and analysis of damaged fishing vessels In the process of righting,the performance indicators such as the floating state,stability and hull girder strength are studied.In the process of correcting the damaged fishing vessel,the secondary damage is caused by the buoyancy,stability,hull girder strength and other indicators beyond the safety range,even directly.The possibility of overturning the hull or breaking the hull girder.2)According to the traditional artificial experience method,the problem of the optimal Counter-flood scheme cannot be obtained quickly,and a method to solve the problem of whether to use the fish tank to straighten the hull and to solve the new solution is proposed.Taking into consideration the safety requirements of various performance indicators(floating state,stability,hull girder strength,etc.)in the process of normalization,a multi-objective optimization mathematical model for the design of fast-rising fishing vessels is established,and the improved multi-objective genetic algorithm is introduced.The NSGA-II algorithm solves it.The algorithm uses a multi-objective evolutionary strategy based on Deb's non-dominated sorting,and proposes a cross-mutation probability assignment method that varies with the number of iterations.Compared with the traditional method of directly solving a multi-objective problem into a single-objective problem(for example,a multi-objective weighted summation method),the setting of the weight coefficient and the normalization coefficient is avoided.Using Matlab software to solve the design problem of the damaged fishing vessel rapid Counter-flood scheme design,a numerical experiment was carried out by taking the design of a damaged fishing right plan of a seine fishing vessel as an example.The experimental results show that the solution of engineering satisfaction can be obtained quickly and efficiently using this method.This method has certain engineering practical value.To sum up,this paper takes the design of the fast Counter-flood scheme for damaged fishing vessels as the research content,and comprehensively considers the safety of various performance indicators of fishing vessels in the course of normalization,and proposes an optimal design method for fast Counter-flood scheme based on multi-objective genetic algorithm.It is hoped that this method can provide some methodological support for the design of damaged fishing vessel righting solutions.