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基于双混频时差法实现时域频率稳定度测量 被引量:2
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作者 谢彦民 马煦 +1 位作者 孔维 孙海燕 《电讯技术》 北大核心 2011年第8期143-146,共4页
在对基于DDS技术的公共振荡器设计、高速数据传输设计以及基于数字测频技术改进等技术难点分析的基础上,论述了基于双混频时差法的时域频率稳定度测量方法。该方法可同时测量短期和长期频率稳定度,测量精度高,并可进行无间隙测量。
关键词 数字测频技术 率稳定度 双混时差法 DDS 无间隙
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Crack detection of reinforced concrete bridge using video image 被引量:8
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作者 许薛军 张肖宁 《Journal of Central South University》 SCIE EI CAS 2013年第9期2605-2613,共9页
With the digital image technology,a crack detection method of reinforced concrete bridge was studied for the performance assessment.The effects including the image gray level,pixel rate,noise filter,and edge detection... With the digital image technology,a crack detection method of reinforced concrete bridge was studied for the performance assessment.The effects including the image gray level,pixel rate,noise filter,and edge detection were analyzed considering cracks qualities.A computer program was developed by visual C++6.0 programming language to detect the cracks,which was tested by 15cases of bridge video images.The results indicate that the relative error is within 6%for cracks larger than 0.3 mm cracks and it is less than 10%for crack width between 0.2 mm and 0.3 mm.In addition,for the crack below 0.1 mm,the relative error is more than30%because the bridge is in safe stage and it is very difficult to detect the actual width of crack. 展开更多
关键词 concrete bridge crack detection computer vision image processing
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