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Analysis of high-power disk laser welding stability based on classification of plume and spatter characteristics 被引量:6
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作者 高向东 文茜 Seiji KATAYAMA 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第12期3748-3757,共10页
Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Ch... Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform. 展开更多
关键词 high-power disk laser welding PLUME SPATTER feature classification STABILITY
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Effects of Heavy Metal and Pollutants on the Non-special Immunity of the Shrimp and Crab
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作者 艾春香 王晓娟 +2 位作者 李少菁 王桂忠 林琼武 《Marine Science Bulletin》 CAS 2008年第1期54-63,共10页
This paper attempted to review and evaluate existing information about the effects of heavy metal, ammonia-N, nitrite and the organic pollutants on the non-special immune response of the shrimp and crab, which providi... This paper attempted to review and evaluate existing information about the effects of heavy metal, ammonia-N, nitrite and the organic pollutants on the non-special immune response of the shrimp and crab, which providing theory for improving the self-immunity of shrimp and crab by meliorating cultural environment. In addition, it could provide information for further study on this field. 展开更多
关键词 Shrimp and crab non-special immune heavy metal POLLUTANTS
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晶格匹配InAlN/GaN异质结Ti/Al/Ni/Au欧姆接触的温度依赖特性
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作者 汪照贤 闫大为 +1 位作者 张丹丹 顾晓峰 《科学通报》 EI CAS CSCD 北大核心 2016年第10期1130-1134,共5页
在硅衬底晶格匹配In_(0.17)Al_(0.83)N/GaN异质结外延片上制备了Ti/Al/Ni/Au欧姆接触传输线模型测试结构,通过测试变温电流-电压特性研究方块电阻(R_(sh))和比接触电阻率(ρ_(sc))的温度依赖特性.结果表明:(1)沟道层的R_(sh)对温度呈指... 在硅衬底晶格匹配In_(0.17)Al_(0.83)N/GaN异质结外延片上制备了Ti/Al/Ni/Au欧姆接触传输线模型测试结构,通过测试变温电流-电压特性研究方块电阻(R_(sh))和比接触电阻率(ρ_(sc))的温度依赖特性.结果表明:(1)沟道层的R_(sh)对温度呈指数依赖关系,幂指数约-2.61,主要由高温下半导体的晶格散射机制决定;(2)300~523 K的变温范围内,ρ_(sc)随温度上升呈先增大后减小的趋势;当温度低于350 K时,ρ_(sc)的温度依赖关系主要由TiN合金的类金属特性决定;而在更高的温度下,热场发射机制将逐渐占主导.基于以上2种模型的并联形式对实验数据进行了拟合,并分析了提取的重要物理参数. 展开更多
关键词 晶格匹配 InAlN/GaN异质结 欧姆接触 温度依赖特性 类金属特性 热场发射
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