本文利用时域特征线算法(characteristic-based time domain method)计算了探针馈电圆柱共形微带天线的输入阻抗和辐射方向图。为减小数值计算误差,直接导出了圆柱坐标系下的相应控制方程,从而将三维方程转换为三个一维方程。计算结果与...本文利用时域特征线算法(characteristic-based time domain method)计算了探针馈电圆柱共形微带天线的输入阻抗和辐射方向图。为减小数值计算误差,直接导出了圆柱坐标系下的相应控制方程,从而将三维方程转换为三个一维方程。计算结果与FDTD算法结果吻合良好,证明了本文理论与数值模型的可行性和精确性。展开更多
本文在圆柱坐标系下通过MAXWELL方程,将三维问题转换为一维问题,产生相应控制方程。利用时域特征线算法(characteristic-based time domain method)计算了探针馈电重叠圆柱共形微带天线的输入阻抗和辐射方向图。本文特点是数值计算误差...本文在圆柱坐标系下通过MAXWELL方程,将三维问题转换为一维问题,产生相应控制方程。利用时域特征线算法(characteristic-based time domain method)计算了探针馈电重叠圆柱共形微带天线的输入阻抗和辐射方向图。本文特点是数值计算误差小,与传统算法相比,缩短了计算时间。计算结果与FDTD算法结果吻合良好,证明了本文理论与数值模型的可行性和精确性。展开更多
This paper discusses the spatial knowledge related to a line ,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line ...This paper discusses the spatial knowledge related to a line ,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line points are presented.These characteristic points are used to improve the algorithms of line generalization.An algorithm for identifying bends is shown.In this paper,improved algorithms based on those by Douglas_Peucker,Visvalingam and Whyatt are shown.In this test,the progressive process of line generalization is emphasized.展开更多
Mainstream line is significant for the Yellow River situation forecasting and flood control.An effective statistical feature extraction method is proposed in this paper.In this method, a between-class scattering matri...Mainstream line is significant for the Yellow River situation forecasting and flood control.An effective statistical feature extraction method is proposed in this paper.In this method, a between-class scattering matrix based projection algorithm is performed to maximize between-class differences, obtaining effective component for classification;then high-order statistics are utilized as the features to describe the mainstream line in the principal component obtained.Experiments are performed to verify the applicability of the algorithm.The results both on synthesized and real scenes indicate that this approach could extract the mainstream line of the Yellow River automatically, and has a high precision in mainstream line detection.展开更多
The paper describes the concept of plaintext encryption by using the Unicode characters. In the case of elliptic curve cryptography, there is not specified rule or algorithm to specify the letters of Tifinagh as well ...The paper describes the concept of plaintext encryption by using the Unicode characters. In the case of elliptic curve cryptography, there is not specified rule or algorithm to specify the letters of Tifinagh as well as special characters. So, the paper gives the transformation of characters Tifinagh into points on elliptic curve by using the corresponding characters Latin. The obtained correspondence has been applied in Menezes-Vanstone cryptosystem based on elliptic curve. Therefore, the paper explains in detail its implementation in Maple 12.展开更多
An efficient algorithm is proposed for factoring polynomials over an algebraic extension field defined by a polynomial ring modulo a maximal ideal. If the maximal ideal is given by its CrSbner basis, no extra Grbbner ...An efficient algorithm is proposed for factoring polynomials over an algebraic extension field defined by a polynomial ring modulo a maximal ideal. If the maximal ideal is given by its CrSbner basis, no extra Grbbner basis computation is needed for factoring a polynomial over this extension field. Nothing more than linear algebraic technique is used to get a characteristic polynomial of a generic linear map. Then this polynomial is factorized over the ground field. From its factors, the factorization of the polynomial over the extension field is obtained. The algorithm has been implemented in Magma and computer experiments indicate that it is very efficient, particularly for complicated examples.展开更多
文摘本文利用时域特征线算法(characteristic-based time domain method)计算了探针馈电圆柱共形微带天线的输入阻抗和辐射方向图。为减小数值计算误差,直接导出了圆柱坐标系下的相应控制方程,从而将三维方程转换为三个一维方程。计算结果与FDTD算法结果吻合良好,证明了本文理论与数值模型的可行性和精确性。
文摘本文在圆柱坐标系下通过MAXWELL方程,将三维问题转换为一维问题,产生相应控制方程。利用时域特征线算法(characteristic-based time domain method)计算了探针馈电重叠圆柱共形微带天线的输入阻抗和辐射方向图。本文特点是数值计算误差小,与传统算法相比,缩短了计算时间。计算结果与FDTD算法结果吻合良好,证明了本文理论与数值模型的可行性和精确性。
文摘This paper discusses the spatial knowledge related to a line ,and the characteristic points of lines is detected.According to the requirements of line generalization,new algorithms for identifying characteristic line points are presented.These characteristic points are used to improve the algorithms of line generalization.An algorithm for identifying bends is shown.In this paper,improved algorithms based on those by Douglas_Peucker,Visvalingam and Whyatt are shown.In this test,the progressive process of line generalization is emphasized.
基金supported by the Flood Control Foundation of Yellow River Conservancy Commissionthe 2007 Key Supporting Project on Undergraduate Graduation Thesis of North-western Polytechnical University.
文摘Mainstream line is significant for the Yellow River situation forecasting and flood control.An effective statistical feature extraction method is proposed in this paper.In this method, a between-class scattering matrix based projection algorithm is performed to maximize between-class differences, obtaining effective component for classification;then high-order statistics are utilized as the features to describe the mainstream line in the principal component obtained.Experiments are performed to verify the applicability of the algorithm.The results both on synthesized and real scenes indicate that this approach could extract the mainstream line of the Yellow River automatically, and has a high precision in mainstream line detection.
文摘The paper describes the concept of plaintext encryption by using the Unicode characters. In the case of elliptic curve cryptography, there is not specified rule or algorithm to specify the letters of Tifinagh as well as special characters. So, the paper gives the transformation of characters Tifinagh into points on elliptic curve by using the corresponding characters Latin. The obtained correspondence has been applied in Menezes-Vanstone cryptosystem based on elliptic curve. Therefore, the paper explains in detail its implementation in Maple 12.
基金supported by National Key Basic Research Project of China (Grant No.2011CB302400)National Natural Science Foundation of China (Grant Nos. 10971217, 60970152 and 61121062)IIE'S Research Project on Cryptography (Grant No. Y3Z0013102)
文摘An efficient algorithm is proposed for factoring polynomials over an algebraic extension field defined by a polynomial ring modulo a maximal ideal. If the maximal ideal is given by its CrSbner basis, no extra Grbbner basis computation is needed for factoring a polynomial over this extension field. Nothing more than linear algebraic technique is used to get a characteristic polynomial of a generic linear map. Then this polynomial is factorized over the ground field. From its factors, the factorization of the polynomial over the extension field is obtained. The algorithm has been implemented in Magma and computer experiments indicate that it is very efficient, particularly for complicated examples.
