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短背射天线矩量法计算中的结头处理
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作者 杨宇森 王华芝 董维仁 《北京邮电学院学报》 CSCD 1991年第4期20-26,共7页
本文给出了一种有效实用的天线结头处理方法.若干计算实例表明它是恰当有效的,特别适用于大量结头的处理.本文利用它完成了短背射天线电特性参数的数值计算;与测量结果相比有较好的一致性.
关键词 短背射天线 矩量法 计算 结头处理
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Classification of Ultrasonic Signs Pre-processed by Fourier Transform through Artificial Neural Network Using the Echo Pulse Technique for the Identification of Defects in Welded Joints of Structural Steel
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作者 Renata Torres Melo Sotero Maria Clea S. de Albuquerque +2 位作者 Francisco G. de Paula Claudia T. T. Farias Eduardo F. de Simas Filho 《Journal of Mechanics Engineering and Automation》 2015年第5期286-290,共5页
It is due to the need to ensure the security and integrity of equipment, that the non-destructive tests have been increasingly used in the industrial sector. Among these, the ultrasonic pulse echo technique is the mos... It is due to the need to ensure the security and integrity of equipment, that the non-destructive tests have been increasingly used in the industrial sector. Among these, the ultrasonic pulse echo technique is the most used in industry, mainly for its simplicity and efficiency. With one transducer only, it is possible to emit the ultrasonic and receive the echo pulse. The ANNs (artificial neural networks) are artificial intelligence techniques that, when properly trained, align themselves to inspection tests becoming a powerful tool in the detection and fault identification. In this work, the echo pulse technique was used to detect discontinuities in welds, where ANNs were fed from the information obtained by digital signal processing techniques (Fourier transform), to identify and classify three distinct classes of defects. Results showed that with the combination of feature extraction by Fourier transformation and classification with neural networks, it is possible to obtain an automatic defect detection system in welded joints with average efficiency. 展开更多
关键词 Non-destructive testing digital signal processing neural networks echo pulse ultrasound.
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