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Dense spacing of the survey lines and slow ship speed (5 knots) provided necessary point density to generate a regular 10 m grid.




 Based on Baba's assumption, the linearized freesurface boundary conditions at low speed are discussed in order to demonstrate the differences between Baba's and Dawson's free surface boundary conditions. By using Fourier integral transformation, a method of computing wave velocity potential φw, which satisfies the boundary conditions of freesurface and hull surface, is presented. The solution of φw is found with the powerful technique of asymptotic expansions, with order compasion method, it is found that... Based on Baba's assumption, the linearized freesurface boundary conditions at low speed are discussed in order to demonstrate the differences between Baba's and Dawson's free surface boundary conditions. By using Fourier integral transformation, a method of computing wave velocity potential φw, which satisfies the boundary conditions of freesurface and hull surface, is presented. The solution of φw is found with the powerful technique of asymptotic expansions, with order compasion method, it is found that the hull surface boundary conditions can be neglected when only the ship wave resistance is concerned. The exact analytical solution of twodemensional slow ship wave velocity potential is derived by neglecting hull effect. The results show that the inhomogeneous effect of freesurface is not negligible in the boundary value problems of slow ship velocity potential.  本文首先从慢船理论的基本假定出发,讨论了Baba与Dawson自由面条件之间的差异;其次,提出了一个求解慢船边值问题的富里埃分析方法,并得到了波动势_(10)的一个渐近级数解;另外,通过进行量级分析,研究了物面条件对_(10)的影响,结果表明物面条件对兴波阻力Rw的影响可以忽略,最后,在不计物面条件的前提下,求到了二维慢船波动势_(10)的一个积分式。  In this paper; based on the theory of qualitative and quantitative differential games, the problem of collision avoidance between two ships is considered. By using the concept of "partial capture region on finite time interval" in [1] and "set covering method" in [2], a new kind of singular curve, semitransition curve, is found and thereby the danger and partial danger regions are constructed. In addition, a solution is given for the problem where the slower ship is an evader. This case was not solved... In this paper; based on the theory of qualitative and quantitative differential games, the problem of collision avoidance between two ships is considered. By using the concept of "partial capture region on finite time interval" in [1] and "set covering method" in [2], a new kind of singular curve, semitransition curve, is found and thereby the danger and partial danger regions are constructed. In addition, a solution is given for the problem where the slower ship is an evader. This case was not solved in [3]. The obtained results show that the method used in this paper is effective and the above two regions are meaningful for practical use.  本文以定性和定量微分对策理论为依据,研究了大型船舶之间的碰撞避免问题。通过采用“有限时间局部捕捉区”的概念和“集合覆盖法”,发现了一种新性质的曲线——半开关曲线,并得到了危险区和局部危险区。此外,本文还对一类尚未解决的慢船躲快船的碰撞避免问题给出一种解答。这些结果表明,本文所使用的方法是有效的,所得到的两种区域是有实际意义的。  The assumption made by Baba and Newman that φot has the same order of magnitude as φox or φoy seems unjustifiable. A better and simpler assumption about the order of magnitude in dimensionless form for the free surface condition in slow ship theory is proposed as: (a) (0) =O(1); (b)ozO(εb),k≥1; (c) φ1 = O (εj),j≥0. Analysis shows that j is equal to 1. It is also found that k is equal to 1 for Baba' s and Newman's free surface condition and for Nakatake' s linearized condition, but fc is greater than 1... The assumption made by Baba and Newman that φot has the same order of magnitude as φox or φoy seems unjustifiable. A better and simpler assumption about the order of magnitude in dimensionless form for the free surface condition in slow ship theory is proposed as: (a) (0) =O(1); (b)ozO(εb),k≥1; (c) φ1 = O (εj),j≥0. Analysis shows that j is equal to 1. It is also found that k is equal to 1 for Baba' s and Newman's free surface condition and for Nakatake' s linearized condition, but fc is greater than 1 for Dawson's linearized condition. Discussions on these boundary conditions are also made.  本文在分析Baba和Newman等人的量级假定的基础上提出了更为合理而简捷的慢船自由面边界条件的量级假定,并用Newman的无量纲化分析方法,分析、讨论了边界条件的几种形式。   << 更多相关文摘 
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