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Parametric rolling prediction in irregular seas using combination of deterministic ship dynamics and probabilistic wave theory 总被引:1,自引:0,他引:1
Atsuo Maki Naoya Umeda Shigeaki Shiotani Eiichi Kobayashi 《Journal of Marine Science and Technology》2011,16(3):294-310
In recent years there have been reports of serious accidents of parametric rolling for modern container ships and car carriers.
For avoiding such accidents, a prediction method of parametric rolling in irregular seas is required. Since parametric rolling
is practically non-ergodic, repetitions of numerical simulations or experiments could be not feasible to ascertain the behaviour.
Therefore, in this paper, a method combining a stochastic approach with a deterministic approach in order to estimate the
probabilistic index without such simple repetitions is developed. The ship's response in regular seas is estimated by solving
an averaged system of the original 1-DoF roll model, and random waves necessary for occurrence of parametric rolling is achieved
by using Longuet-Higgins’s or Kimura’s wave group theory. As a result, a fast and robust computation method of the probabilistic
index is established. Finally, it is concluded that the proposed method is considered to be one of the useful tools for discussing
the new IMO Intact Stability Code. 相似文献
2.
It is very important to estimate the waves generated by a small vessel so as to investigate their effects on floating bodies
within the scope of fisheries and ocean engineering. Simplified methods for estimating the wave heights and periods of ship
waves have been presented in previous studies. However, estimating the direction of ship waves is not easy. The focus of the
present study is to develop an analytical technique to determine the direction of ship waves based on the measurements in
field experiments. The multiple signal classification (MUSIC) method is newly proposed for determining the direction of ship
waves. For high ship speeds, the directional spectrum of ship waves estimated by MUSIC resulted in a sharp monotone peak,
and the estimated directions of ship waves were very similar to the results of field experiments using an actual small vessel.
The proposed MUSIC method has thus been confirmed to be effective in estimating ship wave directions with high resolution. 相似文献
3.
This paper deals with numerical techniques for computing the viscous flow past a ship hull with and without a free surface
using a Reynolds-averaged Navier-Stokes solver with global conservation. In the first technique, a coarse grid is used to
find an approximate solution to the free surface problem. Interpolation of a fine grid is subsequently carried out, and a
more exact solution, particularly in the boundary layer and wake, is obtained. In the second technique, a modified Baldwin-Lomax
model is introduced to compute the viscous flow with and without a free surface. These numerical techniques are applied to
simulations of the flow around a Series 60 and an SR196C ship model. The results are compared with measurement data, and the
usefulness of the numerical techniques is demonstrated. 相似文献
4.
A new weather-routing system that accounts for ship stability based on a real-coded genetic algorithm 总被引:1,自引:0,他引:1
Atsuo Maki Youhei Akimoto Yuichi Nagata Shigenobu Kobayashi Eiichi Kobayashi Shigeaki Shiotani Teruo Ohsawa Naoya Umeda 《Journal of Marine Science and Technology》2011,16(3):311-322
The operation schedule of an oceangoing vessel can be influenced by wave or wind disturbances, and is therefore weather routed.
The weather-routing problem is considered to be a multimodal function problem. Therefore, in the present research, the real-coded
genetic algorithm technique (an evolutionary calculation technique) is applied to globally search for the optimum route. Additionally,
to avoid maritime accidents due to parametric rolling, this route optimization method takes into account the risk of parametric
rolling as one of its objective functions. Numerical verification is carried out for three kinds of objective functions with
different weight ratios between fuel efficiency and ship safety in parametric rolling. As a result, it is numerically confirmed
that the relation between economics and ship safety is a trade-off, and the safer route is not necessarily the most economical.
Considering its robustness, the proposed method appears to be a powerful practical tool by choosing the most appropriate weights
for economics and ship safety. 相似文献
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