中文摘要：

针对船舶纵摇-升沉运动二阶系统的解耦问题,给出二阶系统可对角化的充分必要条件及相应的证明,提出了一种基于同谱构造的船舶纵摇-升沉运动系统的解耦方法.利用解耦前后系统必须同谱的特性,构造了解耦系统的3个参数.通过数值实验实现了一个对称的二阶系统的同谱解耦,结果表明：该解耦方法简便易行,解耦前后系统完全同谱,能够保证运动系统的安全性和稳定性.

英文摘要：

In order to solve the quadratic system decoupling of the ship pitching and heaving motion,giving the necessary and sufficient condition of diagonalizable quadratic system and its corresponding proof,a new decoupling method based on isospectral construction of ship pitching and heaving motion system was proposed in this paper,utilise the characteristic of decoupled system was isospectral with the original system to construct three parameters of the decoupled system,and finally numerical experiment realize the isospectral decoupling of a symmetric quadratic system.The results show that the decoupling method is simple and the decoupled system is isospectral as original system,the security and stability of ship motion can get guarantee.