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A set ofn weighted points in general position in
d
defines a unique regular triangulation. This paper proves that if the points are added one by one, then flipping in a topological order will succeed in constructing this triangulation. If, in addition, the points are added in a random sequence and the history of the flips is used for locating the next point, then the algorithm takes expected time at mostO(nlogn+n
[d/2]). Under the assumption that the points and weights are independently and identically distributed, the expected running time is between proportional to and a factor logn more than the expected size of the regular triangulation. The expectation is over choosing the points and over independent coin-flips performed by the algorithm.The research of both authors was supported by the National Science Foundation under Grant CCR-8921421 and the research by the first author was also supported under the Alan T. Waterman award, Grant CCR-9118874. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the National Science Foundation. 相似文献
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《Journal of Visual Communication and Image Representation》2014,25(2):373-383
Many video fingerprints have been proposed to handle the video transformations problems when the original contents are copied and redistributed. However, most of them did not take into account flipping and rotation transformations. In this paper, we propose a novel video fingerprint based on region binary patterns, aiming to realize robust and fast video copy detection against video transformations including rotation and flipping. We extract two complementary region binary patterns from several rings in keyframes. These two kinds of binary patterns are converted into a new type of patterns for the proposed video fingerprint which is robust against rotation and flipping. The experimental results demonstrated that the proposed video fingerprint is effective for video copy detection particularly in the case of rotation and flipping. Furthermore, our experimental results proved that the proposed method allows for high storage efficiency and low computation complexity, which is suitable for practical video copy system. 相似文献
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Let TS be the set of all crossing-free straight line spanning trees of a planar n-point set S. Consider the graph TS where two members T and T′ of TS are adjacent if T intersects T′ only in points of S or in common edges. We prove that the diameter of TS is O(logk), where k denotes the number of convex layers of S. Based on this result, we show that the flip graph PS of pseudo-triangulations of S (where two pseudo-triangulations are adjacent if they differ in exactly one edge—either by replacement or by removal) has a diameter of O(nlogk). This sharpens a known O(nlogn) bound. Let be the induced subgraph of pointed pseudo-triangulations of PS. We present an example showing that the distance between two nodes in is strictly larger than the distance between the corresponding nodes in PS. 相似文献
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文章针对传统翻译教学存在的一些问题, 提出翻转翻译课堂的必要性和意义, 阐述了翻转翻译课堂的原则
并探讨了基于翻转课堂的翻译教学模式, 以期为提高翻译教学质量提供参考。 相似文献
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为了提高比特翻转(BF)效率,提出一种基于平均幅度的低密度奇偶校验(LDPC)码加权梯度下降比特翻转译码算法。该方法首先以信息节点的平均幅度作为校验方程的可靠度,再用其对双极性校验子进行加权,从而构造出更加高效的比特翻转函数。在加性高斯白噪声(AWGN)信道下,误比特率(BER)为10-5时进行仿真实验,相比传统的梯度下降和基于可靠度比率的加权梯度下降比特翻转算法,所提出的算法可分别获得0.08dB和0.29dB的增益;同时,平均迭代次数可分别降低72.6%和9.3%。实验结果表明,所提算法在获得一定编码增益的同时,平均迭代次数也有所降低,可见该算法在纠错性能、实现复杂度和时延之间达到了更好的平衡匹配,能适用于实时性要求较高的高速通信系统。 相似文献
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Shape Delaunay tessellations are a generalization of the classical Delaunay triangulation of a finite set of points in the plane, where the empty circle condition is replaced by emptiness of an arbitrary convex compact shape. We present some new and basic properties of shape Delaunay tessellations, concerning flipping, subgraph structures, and recognition. 相似文献
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