ABSTRACT
Chaos began in the sixties, American meteorologist E. N. Lorenz obtained a form of movement of fluid in the study of atmospheric convection experiment, and it is an important branch of nonlinear science (Chen and Lu, 2003). In the original concept dynamics, Lorenz system can be seen as velocity, density and temperature distribution function of time, the classical Lorenz dynamics model can be considered to be caused by the turbulence of the marine medium, and the turbulence notable feature is that the system exist the multiple frequencies of oscillation. When the fluid motion, the change of some parameters of the system makes the oscillation coupled, system generates a series of new motion coupling frequency, resulting in the occurrence of chaos (Lan et al., 2013). In recent years the study of underwater acoustic signals show that: when the ship sailing in the ocean medium, the noise generated by hydrodynamic, mechanical noise and propeller noise show a strong nonlinear characteristic, and there are some chaos characteristics(Lorenzo et al., 2002; Li et al., 2012). Therefore, if
the chaos theory is used in the spectral characteristics of the underwater acoustic signal analysis, this will be a significant thing (Vilenchik et al., 2008; Wang et al., 2013a).
