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提出一种针对多波带正交频分复用系统中载波频偏与采样频偏的联合估计算法。为了在频偏较小时获得对噪声干扰足够的鲁棒性,用预偏转技术把频偏预旋转到一个较大的值作估计。该算法在频域处理3个连续相同的前导符,它对频率相关性I/Q失配和频率无关性I/Q失配都具有很好的鲁棒性。基于多波带正交频分复用超宽带无线传输系统的仿真结果,验证了提出的载波频偏和采样频偏联合估计算法的有效性。 相似文献
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In this paper, we begin our research from the generating theory of the medial axis. The normal equidistant mapping relationships between two boundaries and its medial axis have been proposed based on the moving Frenet frames and Cesaro’s approach of the differential geometry. Two pairs of adjoint curves have been formed and the geometrical model of the medial axis transform of the planar domains with curved boundaries has been established. The relations of position mapping, scale transform and differential invariants between the curved boundaries and the medial axis have been investigated. Based on this model, a tracing algorithm for the computation of the medial axis has been generated. In order to get the accurate medial axis and branch points, a Two_Tangent_Points_Circle algorithm and a Three_Tangent_Points_Circle algorithm have been generated, which use the results of the tracing algorithm as the initial values to make the iterative process effective. These algorithms can be used for the computation of the medial axis effectively and accurately. Based on the medial axis transform and the envelope theory, the trimmed offset curves of curved boundaries have been investigated. Several numerical examples are given at the end of the paper. 相似文献
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J. Rafael Sendra 《Journal of Symbolic Computation》2011,46(9):1030-1038
We present algorithms for parametrizing by radicals an irreducible curve, not necessarily plane, when the genus is less than or equal to 4 and the curve is defined over an algebraically closed field of characteristic zero. In addition, we also present an algorithm for parametrizing by radicals any irreducible plane curve of degree d having at least a point of multiplicity d−r, with 1≤r≤4 and, as a consequence, every irreducible plane curve of degree d≤5 and every irreducible singular plane curve of degree 6. 相似文献
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Dong-Yoon Lee Su-Jin Kim Hyun-Chul Kim Sung-Gun Lee Min-Yang Yang 《The International Journal of Advanced Manufacturing Technology》2006,27(7-8):797-803
This paper presents a new paradigm for three-axis tool path generation based on an incomplete two-manifold mesh model; namely,
an inexact polyhedron. When geometric data is transferred from one system to another system and tessellated for tool path
generation, the model does not have any topological data between meshes and facets. In contrast to the existing polyhedral
machining approach, the proposed method generates tool paths from an incomplete two-manifold mesh model. In order to generate
gouge-free tool paths, cutter-location meshes (CL-meshes) are generated by offsetting boundary edges, boundary vertices, and
facets. The CL-meshes are sliced by machining planes and the calculated intersections are sorted, trimmed, and linked. The
grid method is used to reduce the computing time when range searching problems arise. The method is fully implemented and
verified by machining an incomplete two-manifold mesh model. 相似文献
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