In this paper, the difficulties on calculation in solving singular integral equations are overcome when the restriction of curve of integration to be a closed contour is cancelled. When the curve is an open arc and th...In this paper, the difficulties on calculation in solving singular integral equations are overcome when the restriction of curve of integration to be a closed contour is cancelled. When the curve is an open arc and the solutions for singular integral equations possess singularities of higher order, the solution and the solvable condition for characteristic equations as well as the generalized Noether theorem for complete equations are given.展开更多
After choosing weight functions suitably, we define a Banach spaceH ω μ (L) and discuss the generalized inverse of singular integral operators on an open arc. Using the generalized inverse, we obtain the solutions f...After choosing weight functions suitably, we define a Banach spaceH ω μ (L) and discuss the generalized inverse of singular integral operators on an open arc. Using the generalized inverse, we obtain the solutions for the following singular integral equation展开更多
因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Grou...因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Ground-based Tomographic Arc-scanning Synthetic Aperture Radar,GB-TomoArcSAR)通过双轴转台控制天线在不同俯仰角度的水平面内进行圆周扫描来获取高度向合成孔径,实现三维层析成像。本文提出了GB-TomoArcSAR的三维点云生成方法,首先构建了适用于高度向弧形采样条件的层析成像几何模型。其次利用基于巴特沃斯滤波器的奇异值分解(Singular Value Decomposition,SVD)方法进行谱估计,找出层析谱中的峰值及其对应的峰值位置,构成层析向目标候选集。随后利用自对消顺序广义似然比(Sequential Generalized Likelihood Ratio Test with Cancellation,SGLRTC)检测器估计散射体的数目与位置,通过设置检测门限将真实目标的峰值及对应的峰值位置从候选集中筛选出来。最后采用基于空间几何分布的点云优化方法剔除误差点,生成点云图像。文章通过点目标和面目标的仿真实验,验证了所提方法适用于GB-TomoArcSAR,能够有效解决高度向多散射体目标的叠掩问题;进一步开展了实测数据验证,基于所提方法获取了北京市一处建筑基坑的层析点云,其与实际场景几何特征一致。展开更多
为进一步研究故障电弧特征,针对三相电动机及变频器负载开展了串联故障电弧实验。首先将电流信号经过一阶差分预处理,再通过奇异值分解SVD(singular value decomposition)对信号进行两级滤波,剔除信号中的工频和噪声成分。采用柯尔莫可...为进一步研究故障电弧特征,针对三相电动机及变频器负载开展了串联故障电弧实验。首先将电流信号经过一阶差分预处理,再通过奇异值分解SVD(singular value decomposition)对信号进行两级滤波,剔除信号中的工频和噪声成分。采用柯尔莫可洛夫-斯米洛夫K-S(Kolmogorov-Smirnov)检验法分析SVD滤波信号的正态分布情况。采用线性调频Z变换CZT(chirp-Z transform)对SVD滤波信号0~500 Hz频段进行频谱细化分析。提取时域峭度和特征频段幅值平均值组成特征向量,并构建故障电弧区矩形。通过大量数据测试表明:该方法可有效识别三相电动机及变频器负载回路中发生的故障电弧。展开更多
基金Foundation item is supported by the NNSF of China(19971064)
文摘In this paper, the difficulties on calculation in solving singular integral equations are overcome when the restriction of curve of integration to be a closed contour is cancelled. When the curve is an open arc and the solutions for singular integral equations possess singularities of higher order, the solution and the solvable condition for characteristic equations as well as the generalized Noether theorem for complete equations are given.
基金Supported by the National Natural Science Foundation of China( No.2 0 1980 6 33)
文摘After choosing weight functions suitably, we define a Banach spaceH ω μ (L) and discuss the generalized inverse of singular integral operators on an open arc. Using the generalized inverse, we obtain the solutions for the following singular integral equation
文摘因高度向分辨能力缺失,地基干涉雷达应用于建筑成像时会发生严重的高度向叠掩现象。层析合成孔径雷达(Tomographic Synthetic Aperture Radar,TomoSAR)技术具备高度向分辨能力,能够实现建筑三维成像。地基层析圆弧扫描合成孔径雷达(Ground-based Tomographic Arc-scanning Synthetic Aperture Radar,GB-TomoArcSAR)通过双轴转台控制天线在不同俯仰角度的水平面内进行圆周扫描来获取高度向合成孔径,实现三维层析成像。本文提出了GB-TomoArcSAR的三维点云生成方法,首先构建了适用于高度向弧形采样条件的层析成像几何模型。其次利用基于巴特沃斯滤波器的奇异值分解(Singular Value Decomposition,SVD)方法进行谱估计,找出层析谱中的峰值及其对应的峰值位置,构成层析向目标候选集。随后利用自对消顺序广义似然比(Sequential Generalized Likelihood Ratio Test with Cancellation,SGLRTC)检测器估计散射体的数目与位置,通过设置检测门限将真实目标的峰值及对应的峰值位置从候选集中筛选出来。最后采用基于空间几何分布的点云优化方法剔除误差点,生成点云图像。文章通过点目标和面目标的仿真实验,验证了所提方法适用于GB-TomoArcSAR,能够有效解决高度向多散射体目标的叠掩问题;进一步开展了实测数据验证,基于所提方法获取了北京市一处建筑基坑的层析点云,其与实际场景几何特征一致。
文摘为进一步研究故障电弧特征,针对三相电动机及变频器负载开展了串联故障电弧实验。首先将电流信号经过一阶差分预处理,再通过奇异值分解SVD(singular value decomposition)对信号进行两级滤波,剔除信号中的工频和噪声成分。采用柯尔莫可洛夫-斯米洛夫K-S(Kolmogorov-Smirnov)检验法分析SVD滤波信号的正态分布情况。采用线性调频Z变换CZT(chirp-Z transform)对SVD滤波信号0~500 Hz频段进行频谱细化分析。提取时域峭度和特征频段幅值平均值组成特征向量,并构建故障电弧区矩形。通过大量数据测试表明:该方法可有效识别三相电动机及变频器负载回路中发生的故障电弧。
