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采用向量匹配法的油纸绝缘系统扩展Debye模型参数识别 被引量:21
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作者 汤明杰 雷敏 +3 位作者 白帆 魏建林 许昊 张冠军 《高电压技术》 EI CAS CSCD 北大核心 2014年第2期548-556,共9页
为了从时域数据中获取更丰富的表征油纸绝缘系统绝缘状态的信息,提出了一种获取油纸绝缘系统扩展Debye模型参数的方法。首先通过快速Fourier变换(FFT)获得极化去极化电流(PDC)实验的去极化电流频谱,然后使用向量匹配法(VFM)和时域非线... 为了从时域数据中获取更丰富的表征油纸绝缘系统绝缘状态的信息,提出了一种获取油纸绝缘系统扩展Debye模型参数的方法。首先通过快速Fourier变换(FFT)获得极化去极化电流(PDC)实验的去极化电流频谱,然后使用向量匹配法(VFM)和时域非线性拟合算法(FNA),确定其频谱的极点和留数分布,最后根据极点和留数计算得到各支路参数。针对实验室不同老化程度和不同温度下的油纸绝缘模型,开展了验证性的PDC和频谱(FDS)实验,利用PDC实验数据求取了相应的扩展Debye模型,据此获得了介损(tanδ)随频率的变化曲线,并与FDS所得结果进行了比较。结果表明,PDC所得结果与FDS曲线在低频段一致,验证了所提方法的正确性。进而提出在对油纸绝缘设备绝缘状况进行测试时,采用FDS做高频测试,而采用PDC代替FDS做低频测试,从而减少测试时间,即将PDC与FDS这2种方法相结合,可以提高现场油纸绝缘设备的检测效率。 展开更多
关键词 油纸绝缘 扩展Debye模型 参数识别 快速FOURIER变换 向量匹配 极化去极化电流 频域介电谱
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盘形圆弧砂轮曲面磨削几何模型 被引量:1
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作者 彭扬林 戴一帆 +1 位作者 宋辞 石峰 《国防科技大学学报》 EI CAS CSCD 北大核心 2015年第6期39-42,共4页
砂轮外形、加工轨迹、运动轴组合方式、工件摆放方式等的差异都会引起曲面磨削加工模型的变化,加工几何模型是实施曲面磨削首要解决的问题。建立盘形圆弧砂轮的几何模型,通过磨削点法向量匹配,建立工件点和砂轮点的一一映射关系,经过坐... 砂轮外形、加工轨迹、运动轴组合方式、工件摆放方式等的差异都会引起曲面磨削加工模型的变化,加工几何模型是实施曲面磨削首要解决的问题。建立盘形圆弧砂轮的几何模型,通过磨削点法向量匹配,建立工件点和砂轮点的一一映射关系,经过坐标变换可以得到相应的刀具运动轨迹,用于磨削加工。形成统一的盘形砂轮曲面磨削几何模型,并给出刀具运动轨迹的计算流程。该磨削模型适用范围广,有效解决了多种曲面磨削过程的刀具轨迹生成问题,实现了高精度的曲面磨削加工。 展开更多
关键词 曲面磨削 磨削几何模型 砂轮模型 法向量匹配
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基于特征点和BCH码的大容量水印嵌入方案
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作者 孙文静 陈建华 章无用 《电子技术与软件工程》 2017年第8期79-81,82,共4页
针对目前大部分水印算法嵌入容量小、抗剪切等几何攻击性能差的缺点,提出一种利用特征点对匹配关系进行图像矫正,并通过BCH码进行纠错的大容量水印嵌入方案。本方案利用SURF算法从原始图像和受攻击图像中分别提取特征点,结合向量匹配法... 针对目前大部分水印算法嵌入容量小、抗剪切等几何攻击性能差的缺点,提出一种利用特征点对匹配关系进行图像矫正,并通过BCH码进行纠错的大容量水印嵌入方案。本方案利用SURF算法从原始图像和受攻击图像中分别提取特征点,结合向量匹配法及RANSAC算法进行误匹配特征点对排除,根据特征点对间的坐标关系,用最小二乘法拟合出仿射矩阵进行图像矫正。实验结果表明,本算法具有水印嵌入容量大、鲁棒性强、透明性好等特点。 展开更多
关键词 BCH码 SURF特征点 向量匹配 RANSAC算
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Information hiding scheme for vector maps based on fingerprint certification
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作者 门朝光 孙建国 曹刘娟 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第6期766-770,共5页
An information hiding scheme for vector maps is presented to identify the source after the vector map is leaked in some key application areas. In this scheme, the fingerprint image of the map owner can be converted in... An information hiding scheme for vector maps is presented to identify the source after the vector map is leaked in some key application areas. In this scheme, the fingerprint image of the map owner can be converted into a character string as the watermark, and then the watermark will be embedded into the coordinate descriptions of the attribute file by the "0-bit value" programming method. This programming algorithm ensures that the accuracy is lossless and the graphics is unchanged for any vector map. Experiments show that the presented hiding scheme has stable robustness, the average similarity rate is 97.2% for fingerprints matching and the false non-match rate is 1.38% in the blocking test. In the opening test, the former reaches 84.46% and the latter reaches 5.56%. 展开更多
关键词 information hiding digital watermarking vector map FINGERPRINT AUTHENTICATION
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A REAL-TIME C-V CLUSTERING ALGORITHM FOR WEB-MINING
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作者 Li Haiying Zhuang Zhenquan Li Bin Wan Ke (Dept. of Electronic S &T, University of Science and Technology of China, HeFei 230026) 《Journal of Electronics(China)》 2002年第1期71-75,共5页
In this letter, a real-time C-V (Characteristic-Vector) clustering algorithm is put forth to treat with vast action data which are dynamically collected from web site. The algorithm cites the concept of C-V to denote ... In this letter, a real-time C-V (Characteristic-Vector) clustering algorithm is put forth to treat with vast action data which are dynamically collected from web site. The algorithm cites the concept of C-V to denote characteristic, synchronously it adopts two-value [0,1]input and self-definition vigilance parameter to design clustering-architecture. Vector Degree of Matching (VDM) plays a key role in the clustering algorithm, which determines the magnitude of typical characteristic. Making use of stability analysis, the classifications are confirmed to have reliably hierarchical structure when vigilance parameter shifts from 0.1 to 0.99. This non-linear relation between vigilance parameter and classification upper limit helps mining out representative classifications from net-users according to the actual web resource, then administering system can map them to web resource space to implement the intelligent configuration effectually and rapidly. 展开更多
关键词 Clustering algorithm Characteristic-vector Vector degree of matching
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Face Orientation Normalization Using Eye Positions 被引量:2
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作者 Audrius Bukis Rimvydas Simutis 《Computer Technology and Application》 2013年第10期513-521,共9页
Despite the fact that progress in face recognition algorithms over the last decades has been made, changing lighting conditions and different face orientation still remain as a challenging problem. A standard face rec... Despite the fact that progress in face recognition algorithms over the last decades has been made, changing lighting conditions and different face orientation still remain as a challenging problem. A standard face recognition system identifies the person by comparing the input picture against pictures of all faces in a database and finding the best match. Usually face matching is carried out in two steps: during the first step detection of a face is done by finding exact position of it in a complex background (various lightning condition), and in the second step face identification is performed using gathered databases. In reality detected faces can appear in different position and they can be rotated, so these disturbances reduce quality of the recognition algorithms dramatically. In this paper to increase the identification accuracy we propose original geometric normalization of the face, based on extracted facial feature position such as eyes. For the eyes localization lbllowing methods has been used: color based method, mean eye template and SVM (Support Vector Machine) technique. Experimental investigation has shown that the best results for eye center detection can be achieved using SVM technique. The recognition rate increases statistically by 28% using face orientation normalization based on the eyes position. 展开更多
关键词 Face recognition support vector machine orientation normalization and facial features
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