文中在MU S IC算法的基础上,建立了平面任意形状阵列二维超分辨测向的数学模型及通用算法。针对不同天线阵列结构对二维测向性能的影响问题,分别以双排均匀线阵、均匀圆阵、均匀正方形阵和均匀L阵为模型进行了计算机仿真实验,并对这几...文中在MU S IC算法的基础上,建立了平面任意形状阵列二维超分辨测向的数学模型及通用算法。针对不同天线阵列结构对二维测向性能的影响问题,分别以双排均匀线阵、均匀圆阵、均匀正方形阵和均匀L阵为模型进行了计算机仿真实验,并对这几种阵列的二维测角精度和稳健性进行了较全面的比较分析,得出了较理想的阵列设计方案。展开更多
An alternative method is proposed in this letter for describing the arbitrary shape and size for granules in 2D image.After image binarization, the edge points on contour are detected, by which the centroid of the sha...An alternative method is proposed in this letter for describing the arbitrary shape and size for granules in 2D image.After image binarization, the edge points on contour are detected, by which the centroid of the shape in question is sought using the moment calculation.Using Principal Component Analysis(PCA), the major and minor diameters are computed.Based on the signature curve-fitting, the first-order derivative is taken so as to seek all the characteristic vertices.By connecting the vertices found, the simplified polygon is formed and utilized for shape and size descriptive purposes.The developed algorithm is run on two given real particle images, and the execution results indicate that the computed parameters can technically well describe the shape and size for the original particles, being able to provide a ready-to-use database for machine vision system to perform related data processing tasks.展开更多
By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite reg...By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite region, and obtains stress and displacement fields for random times of iteration. After precision analysis it is found that the results for twenty times of iteration are of very high precision, and those with higher precision can be acquired if the iteration solving is further conducted. The comparison of the results from FEM further proves the reliability of the simplified alternating algorithm presented by this paper.展开更多
According to the combination of the complementary medium and transformation optics, the shape of two-dimensional (2D) internal-external cloaks has been generalized into any geometry to adapt to the variety of object s...According to the combination of the complementary medium and transformation optics, the shape of two-dimensional (2D) internal-external cloaks has been generalized into any geometry to adapt to the variety of object shapes. In order to adapt to the practical application, some approximations have been introduced to eliminate the infinite singularity of the parameters in the compressed region by adjusting the principle sketch out of the plane. Firstly, the general parameter equations of the nonsingular cloak with arbitrary cross-section are deduced strictly by the mathematical method based on coordinate transformations in the cylindrical coordinate system. Secondly, taking into account the discontinuous property of the curve functions of arbitrary polygons, a supplementary investigation is given for the nonsingular cloak with arbitrary polygonal cross-section. The transformations in the supplementary study are carried out in the Cartesian coordinate system directly and referred to the coordinates of the polygon's vertices rather than the curve function of the polygon. Last, the invisibility effect of the corresponding cloak is studied by full-wave simulations based on the finite element method. The applicable scope of the 2D internal-external cloak is expanded greatly by the methods and results given in this paper.展开更多
文摘文中在MU S IC算法的基础上,建立了平面任意形状阵列二维超分辨测向的数学模型及通用算法。针对不同天线阵列结构对二维测向性能的影响问题,分别以双排均匀线阵、均匀圆阵、均匀正方形阵和均匀L阵为模型进行了计算机仿真实验,并对这几种阵列的二维测角精度和稳健性进行了较全面的比较分析,得出了较理想的阵列设计方案。
基金Supported by the Ningbo Natural Science Foundation (No.2006A610016)
文摘An alternative method is proposed in this letter for describing the arbitrary shape and size for granules in 2D image.After image binarization, the edge points on contour are detected, by which the centroid of the shape in question is sought using the moment calculation.Using Principal Component Analysis(PCA), the major and minor diameters are computed.Based on the signature curve-fitting, the first-order derivative is taken so as to seek all the characteristic vertices.By connecting the vertices found, the simplified polygon is formed and utilized for shape and size descriptive purposes.The developed algorithm is run on two given real particle images, and the execution results indicate that the computed parameters can technically well describe the shape and size for the original particles, being able to provide a ready-to-use database for machine vision system to perform related data processing tasks.
基金the National Natural Science Foundation of China (Grant No. 49772166).
文摘By using Schwarz alternating method, this paper presents asimplified alternating algorithm for the problems of two holes having arbitrary shapes and arrangements in an isotropic homogeneous linear elastic infinite region, and obtains stress and displacement fields for random times of iteration. After precision analysis it is found that the results for twenty times of iteration are of very high precision, and those with higher precision can be acquired if the iteration solving is further conducted. The comparison of the results from FEM further proves the reliability of the simplified alternating algorithm presented by this paper.
文摘According to the combination of the complementary medium and transformation optics, the shape of two-dimensional (2D) internal-external cloaks has been generalized into any geometry to adapt to the variety of object shapes. In order to adapt to the practical application, some approximations have been introduced to eliminate the infinite singularity of the parameters in the compressed region by adjusting the principle sketch out of the plane. Firstly, the general parameter equations of the nonsingular cloak with arbitrary cross-section are deduced strictly by the mathematical method based on coordinate transformations in the cylindrical coordinate system. Secondly, taking into account the discontinuous property of the curve functions of arbitrary polygons, a supplementary investigation is given for the nonsingular cloak with arbitrary polygonal cross-section. The transformations in the supplementary study are carried out in the Cartesian coordinate system directly and referred to the coordinates of the polygon's vertices rather than the curve function of the polygon. Last, the invisibility effect of the corresponding cloak is studied by full-wave simulations based on the finite element method. The applicable scope of the 2D internal-external cloak is expanded greatly by the methods and results given in this paper.
