Estimation of coefficients of the equation of nonlinear roll motion for fishing boats by improved energy method and genetic algorithm

2003 ◽  
Vol 20 (2) ◽  
pp. 155-192 ◽  
Author(s):  
Kimihiko Ueno ◽  
Nobuo Kimura ◽  
Kiyoshi Amagai
Keyword(s):  
Genetic Algorithm ◽  
Energy Method ◽  
Roll Motion ◽  
Nonlinear Roll Motion

The Optimization of Curve Based on Genetic Algorithm and Energy Method

2011 ◽  
Vol 338 ◽  
pp. 227-230
Author(s):  
Gang He ◽  
Zheng Yu Pan ◽  
Deng Lin Zhu
Keyword(s):  
Genetic Algorithm ◽  
Energy Method ◽  
Optimization Method ◽  
Crossover Operator ◽  
Curve Networks

An optimization method based on genetic algorithm and energy method is presented to construct a fairing curve network from unconnected sectional curves. The curve’s quality is evaluated by its energy. The parameters of the intersecting points on existing curves are adopted as variable and genetic algorithm is used to optimize the energy of curve based on multi-parent crossover operator. The examples show that the interpolated surface of optimized curve network has good quality than other methods, which proves our method actually improves curve networks’ quality.

Long-Term Extreme Response of a Vessel Rolling in Random Seas

2016 ◽  
Author(s):  
Wei Chai ◽  
Arvid Naess ◽  
Bernt J. Leira
Keyword(s):  
Nonlinear Effects ◽  
Roll Motion ◽  
Response Analysis ◽  
Linear Filter ◽  
Beam Seas ◽  
Random Seas ◽  
Extreme Response ◽  
High Level ◽  
Nonlinear Roll Motion

In this paper, the long-term extreme response of a vessel rolling in random beam seas is addressed. The long-term response analysis is based on the upcrossing rates of the roll motion under different sea states. However, the nonlinear effects associated with the restoring and damping terms have a significant influence on the high-level response, assessing the corresponding statistics, such as the upcrossing rate, with low probability levels is difficult and time-consuming. In this work, the Markov theory is introduced in order to tackle this problem. Specifically, the random roll excitation moment is approximated as a filtered white noise process by applying a linear filter technique and an efficient four-dimensional (4D) path integration (PI) procedure is applied in order to calculate the response statistics. The long-term analysis of nonlinear roll motion in random seas that takes into considerations of the response statistics obtained by the 4D PI method as well as the variation of the sea states could be a valuable reference for ship stability research.

Sign in / Sign up

Export Citation Format

Share Document