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遗传系谱图的快准识别
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作者 汪云峰 《科教导刊》 2019年第19期40-41,共2页
遗传系谱图的识别是高中生学习遗传学不可或缺的重要基础内容之一,是常考的知识点。遗传系谱图的识别影响学生的生物成绩,更影响理科综合总分。如何快速准确地教会学生识别遗传系谱图,也是许多高中生物教师一直所面临的教学难题。
关键词 高中生物 遗传系谱图 快准识别
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A synthetic criterion for early recognition of cutting chatter 被引量:5
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作者 JIA GuangFei WU Bo +2 位作者 HU YouMin XIE FengYun LIU Ao 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第11期2870-2876,共7页
Cutting chatter is a violent self-excited vibration between a tool and a workpiece.Its negative effects mainly include poor surface quality,inferior dimensional accuracy,disproportionate tool wear or tool breakage,and... Cutting chatter is a violent self-excited vibration between a tool and a workpiece.Its negative effects mainly include poor surface quality,inferior dimensional accuracy,disproportionate tool wear or tool breakage,and excessive noise.Therefore,early recognition and online suppression of chatter vibration are necessary.This paper proposes a novel synthetic criterion(SC)for early chatter recognition.The proposed SC integrates standard deviation(STD)and one-step autocorrelation function(OSAF).Moreover,this paper revised the fast algorithm of OSAF.We can quantitatively divide a chatter vibration signal into three stages,which are stable stage,transition stage and chatter stage according to the SC.Compared with STD,the SC can improve the reliability of chatter recognition and the threshold of SC is not sensitive to variable cutting conditions.This paper presents an original algorithm of SC and its fast algorithm in detail.The fast algorithm of SC in this paper improves the computation efficiency compared with the original algorithm of SC.To validate the effectiveness of the proposed SC,a series of milling experiments were conducted under different cutting conditions.In these experiments,the vibration signals were acquired by two accelerometers mounted on the spindle house.The experimental results showed that the proposed SC could effectively recognize chatter vibration at an early stage of chatter vibration,which saved valuable time for online chatter suppression. 展开更多
关键词 cutting chatter chatter recognition feature extraction synthetic criterion
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