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变截面圆柱形空腔覆盖层吸声系数的二维近似解 被引量:28
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作者 何世平 汤渭霖 +1 位作者 何琳 汤智胤 《船舶力学》 EI 北大核心 2006年第1期120-127,共8页
具有空腔周期性排列的粘弹性结构在水声工程中有着广泛的应用。将包含变截面圆柱形空腔周期性排列的吸声覆盖层的一个单元进行分段近似成多层圆柱管结构,并应用子域分割法在分段的接合界面处满足平均轴向位移和平均轴向应力连续,给出了... 具有空腔周期性排列的粘弹性结构在水声工程中有着广泛的应用。将包含变截面圆柱形空腔周期性排列的吸声覆盖层的一个单元进行分段近似成多层圆柱管结构,并应用子域分割法在分段的接合界面处满足平均轴向位移和平均轴向应力连续,给出了变截面圆柱形空腔吸声覆盖层吸声系数的二维近似解。分析了高阶传播波和分段层数对吸声系数的影响,比较了不同空腔形状对覆盖层吸声性能的影响。研究结果表明,在一定频率范围内,主要是最低阶传播模式对吸声性能起作用,喇叭型空腔结构较圆柱型空腔结构吸声覆盖层的吸声性能更加优良。在覆盖层设计中,空腔的形状应有一个优化的过程。 展开更多
关键词 吸声覆盖层 变截面圆柱形空腔 子域分割法 吸声系数
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Flotation bubble image segmentation based on seed region boundary growing 被引量:4
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作者 Zhang Guoying Zhu Hong Xu Ning 《Mining Science and Technology》 EI CAS 2011年第2期239-242,共4页
Segmenting blurred and conglutinated bubbles in a flotation image is done using a new segmentation method based on Seed Region and Boundary Growing(SRBG).Bright pixels located on bubble tops were extracted as the se... Segmenting blurred and conglutinated bubbles in a flotation image is done using a new segmentation method based on Seed Region and Boundary Growing(SRBG).Bright pixels located on bubble tops were extracted as the seed regions.Seed boundaries are divided into four curves:left-top,right-top,right-bottom, and left-bottom.Bubbles are segmented from the seed boundary by moving these curves to the bubble boundaries along the corresponding directions.The SRBG method can remove noisy areas and it avoids over- and under-segmentation problems.Each bubble is segmented separately rather than segmenting the entire flotation image.The segmentation results from the SRBG method are more accurate than those from the Watershed algorithm. 展开更多
关键词 Bubble image SEGMENTATION Seed area Region growing
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