Wing kinematics in forward-flying fruit-flies was measured using high-speed cameras and flows of the flapping wing were calculated numerically. The large lift and thrust coefficients produced by the wing were explaine...Wing kinematics in forward-flying fruit-flies was measured using high-speed cameras and flows of the flapping wing were calculated numerically. The large lift and thrust coefficients produced by the wing were explained. The wing flaps along a forward-tilting stroke plane. In the starting portion of a half-stroke （an upstroke or downstroke）, the wing pitches down to a small pitch angle; during the mid portion （the wing has built up its speed）, it first fast pitches up to a large pitch angle and then maintains the pitch angle; in the ending portion, the wing pitches up further. A large aerodynamic force （normal to the wing surface） is produced during the mid portion of a half-stroke. The large force is produced by the fast-pitching-up rotation and delayed-stall mechanisms. As a result of the orientation of wing, the thrust that propels the insect is produced by the upstroke and the major part of the vertical force that supports the weight is produced by the downstroke. In producing the thrust the upstroke leaves a ＂vortex ring＂ that is almost vertical, and in producing the vertical force the downstroke leaves a ＂vortex ring＂ that is almost horizontal.展开更多
针对乳腺肿瘤良恶性二值分类的特点,提出了一种基于修正的果蝇优化算法和支持向量机(MFOASVM)的乳腺肿瘤识别方法.为提高SVM分类器的泛化性能,将MFOA算法引入SVM,进而优化SVM中的惩罚参数和核函数参数.为了综合评估提出算法的有效性,在...针对乳腺肿瘤良恶性二值分类的特点,提出了一种基于修正的果蝇优化算法和支持向量机(MFOASVM)的乳腺肿瘤识别方法.为提高SVM分类器的泛化性能,将MFOA算法引入SVM,进而优化SVM中的惩罚参数和核函数参数.为了综合评估提出算法的有效性,在威斯康新诊断乳腺癌(Wisconsin diagnostic breast cancer,WDBC)数据集进行了实验对比分析.实验结果表明:MFOA-SVM与BP,LVQ及PSO-SVM 3种方法相比,其分类准确性和稳定性显著提高.展开更多
基金This research was supported by a grant from the National Natural Science Foundation of China （11232002）.
文摘Wing kinematics in forward-flying fruit-flies was measured using high-speed cameras and flows of the flapping wing were calculated numerically. The large lift and thrust coefficients produced by the wing were explained. The wing flaps along a forward-tilting stroke plane. In the starting portion of a half-stroke （an upstroke or downstroke）, the wing pitches down to a small pitch angle; during the mid portion （the wing has built up its speed）, it first fast pitches up to a large pitch angle and then maintains the pitch angle; in the ending portion, the wing pitches up further. A large aerodynamic force （normal to the wing surface） is produced during the mid portion of a half-stroke. The large force is produced by the fast-pitching-up rotation and delayed-stall mechanisms. As a result of the orientation of wing, the thrust that propels the insect is produced by the upstroke and the major part of the vertical force that supports the weight is produced by the downstroke. In producing the thrust the upstroke leaves a ＂vortex ring＂ that is almost vertical, and in producing the vertical force the downstroke leaves a ＂vortex ring＂ that is almost horizontal.
文摘针对乳腺肿瘤良恶性二值分类的特点,提出了一种基于修正的果蝇优化算法和支持向量机(MFOASVM)的乳腺肿瘤识别方法.为提高SVM分类器的泛化性能,将MFOA算法引入SVM,进而优化SVM中的惩罚参数和核函数参数.为了综合评估提出算法的有效性,在威斯康新诊断乳腺癌(Wisconsin diagnostic breast cancer,WDBC)数据集进行了实验对比分析.实验结果表明:MFOA-SVM与BP,LVQ及PSO-SVM 3种方法相比,其分类准确性和稳定性显著提高.
