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Yukinobu Nagata Koji Gotoh Masahiro Toyosada 《Journal of Marine Science and Technology》2009,14(1):104-114
Many accidents are caused by fatigue in welded built-up steel structures, and so it is important to estimate the fatigue lives
of such structures quantitatively for safety reasons. By assuming that fatigue cracks cannot grow without an accumulation
of alternating tensile/compressional plastic strain, one of the authors identified an improved effective stress intensity
factor range ΔK
RPG based on the re-tensile plastic zone generating (RPG) load, which represents the driving force for fatigue cracks, and suggested
that ΔK
RPG should be used as the parameter to describe fatigue crack growth behavior. The “FLARP” numerical simulation code in which
ΔK
RPG is implemented as the fatigue crack growth parameter, was developed in order to predict fatigue crack initiation and propagation
behavior. In this paper, it is demonstrated that FLARP gives accurate estimates for fatigue life by comparing the estimated
fatigue crack growth curves and S–N curves with the experimental results for in-plane gusset welded joints, which are used in many welded steel structures. Moreover,
the effect of induced bending moment due to the linear misalignment in the out of plane direction on the fatigue strength
of in-plane gusset welded joints is investigated through numerical simulations. 相似文献
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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
3.
Near infrared (NIR) hyperspectral imaging measurement of sugar content in peach was introduced. NIR spectral images (650~1 000 nm, resolution: 2 nm) of peach samples were captured with developed hyperspectral imaging setup. Partial least square (PLS) regression prediction model was developed to estimate the sugar content in peach; step-wise backward method was utilized to determine optimal wavelength subsets. Experimental results show that the calibration model with optimal wavelength subsets has a correlation coefficient of prediction of 0.97 and a standard error of prediction of 0.19, the prediction accuracy is higher than the calibration model applied over the whole wavelength, which proves that variable selection plays an important role in improving the prediction accuracy of PLS regression model. 相似文献
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