Numerical Study of the Ice Breaking Resistance of the Icebreaker in the Yellow River Through Smoothed-Particle Hydrodynamics

A ship-ice-water interaction model is established using smoothed-particle hydrodynamics(SPH)to predict the ice breaking resistance of the icebreaker in the Yellow River effectively.This method includes the numerical process of the constitutive equation,yield criterion,and the coupling model in SPH.The ice breaking resistance is determined under different conditions.The numerical results of the ice breaking resistance agree with the empirical formula results.Results show that the prediction accuracy of ice resistance is less than 17.6%compared with the empirical formula in the level ice.The method can also be extended to predict the floe motion and ice breaking resistance in actual river channels.The validation against the empirical formula indicates that the proposed ship-ice-water SPH method can predict the ice breaking resistance of icebreakers in actual rivers effectively.The predicted ice breaking resistance is analyzed under different conditions.The ice breaking resistance increases with increasing bending strength and ice thickness,and the latter is the most important factor influencing ice resistance.

Contrasting Characteristics of Lodging Resistance in Two Super-Rice Hybrids Differing in Harvest Index

The“super rice”breeding program in China has been successful in developing high-yielding hybrids,including few with high harvest index values.However,there is limited information on the relationship between lodging resistance and harvest index,and the mechanisms underlying the relationship in super-rice hybrids.In this study,a two-year field experiment was conducted to compare lodging resistance and its related traits between two superrice hybrids differing in harvest index,i.e.,Guiliangyou 2(G2)with a high harvest index and Y-liangyou 1(Y1)with a typical harvest index of modern high-yielding rice varieties.Results showed that compared to Y1,G2 was lower in plant height due to its lower aboveground N uptake,and its higher stem breaking resistance(i.e.,lower stem breaking index)resulted from a lower stem height at its center of gravity.Consequently,G2 had a higher lodging resistance(i.e.,lower plant lodging index)than Y1.This study suggests that developing super-rice hybrids with high harvest index values is a possible way to achieve both high grain yield and strong lodging resistance in rice.