共查询到20条相似文献,搜索用时 0 毫秒
1.
Xiao-Diao Chen Author Vitae Jun-Hai Yong Author Vitae Guo-Qin Zheng Author Vitae Jia-Guang Sun Author Vitae 《Computer aided design》2004,36(12):1205-1218
A method for generating an interpolation closed G1 arc spline on a given closed point set is presented. For the odd case, i.e. when the number of the given points is odd, this paper disproves the traditional opinion that there is only one closed G1 arc spline interpolating the given points. In fact, the number of the resultant closed G1 arc splines fulfilling the interpolation condition for the odd case is exactly two. We provide an evaluation method based on the arc length as well such that the choice between those two arc splines is made automatically. For the even case, i.e. when the number of the given points is even, the points are automatically moved based on weight functions such that the interpolation condition for generating closed G1 arc splines is satisfied, and that the adjustment is small. And then, the G1 arc spline is constructed such that the radii of the arcs in the spline are close to each other. Examples are given to illustrate the method. 相似文献
2.
3.
Lin Chen 《Algorithmica》1993,9(3):217-238
We present the first efficient parallel algorithms for recognizing some subclasses of circular arc graphs including circular arc graphs and proper interval graphs. These algorithms run in O(log2
n) time withO(n
3) processors on a CRCW PRAM. An intersection representation can also be constructed within the same resource bounds. Furthermore, we propose some new characterizations of circular arc graphs and proper interval graphs.Portions of this paper have appeared in preliminary form in theProceedings of the 1989 IEEE international Symposium on Circuits and Systems [9], theProceedings of the 1989 Workshop on Algorithms and Data Structures [10], and theProceedings of the 1990 Canadian Conference on Computational Geometry [11]. 相似文献
4.
5.
The intention of this note is to motivate the researchers to study Hadwiger's conjecture for circular arc graphs. Let η(G) denote the largest clique minor of a graph G, and let χ(G) denote its chromatic number. Hadwiger's conjecture states that η(G)?χ(G) and is one of the most important and difficult open problems in graph theory. From the point of view of researchers who are sceptical of the validity of the conjecture, it is interesting to study the conjecture for graph classes where η(G) is guaranteed not to grow too fast with respect to χ(G), since such classes of graphs are indeed a reasonable place to look for possible counterexamples. We show that in any circular arc graph G, η(G)?2χ(G)−1, and there is a family with equality. So, it makes sense to study Hadwiger's conjecture for this family. 相似文献
6.
《国际计算机数学杂志》2012,89(10):2152-2162
A strongly connected digraph D is hyper-λ if the removal of any minimum arc cut of D results in exactly two strong components, one of which is a singleton. We define a hyper-λ digraph D to be m-hyper-λ if D?S is still hyper-λ for any arc set S with ∣S∣≤m. The maximum integer of such m, denoted by Hλ(D), is said to be the arc fault tolerance of D on the hyper-λ property. Hλ(D) is an index to measure the reliability of networks. In this paper, we study Hλ(D) for the cartesian product digraph D=D1×D2. We give a necessary and sufficient condition for D1×D2 to be hyper-λ and give the lower and upper bounds on Hλ(D1×D2). An example shows that the lower and upper bounds are best possible. In particular, exact values of Hλ(D1×D2) are obtained in special cases. These results are also generalized to the cartesian product of n strongly connected digraphs. 相似文献
7.
Yair Shoham 《International Journal of Speech Technology》1999,2(4):329-341
Low-rate speech coding technology has recently made a significant progress with the introduction of new interpolative algorithms (Shoham, 1993; Kleijn and Haagen, 1995). The inherent complexity of these algorithms is, however too high too be commercially useful for low-cost applications. In this paper we propose new approaches to low-complexity speech coding at coding rates of 1.2 and 2.4 kbps. The proposed methods utilize all the advantages of interpolatve coding but greatly simplify the analysis and synthesis operations to a point where low-cost two-way digital speech communication can be easily implemented on DSP or host platforms. At 2.4 kbps, the complexity of the proposed coder is about 7.5 and 2.5 MFLOPS for the encoder and decoder, respectively. At 1.2 kbps, the complexity is about 6 and 2.3 MFLOPS for the encoder and decoder, respectively. The small computational load of these coders make them suitable for multi-tasking environment and low-cost terminals. Informal subjective evaluation shows that, at 2.4 kbps, good communication quality is obtained. Communication quality is less than toll quality but the perceived coding effects are not annoying and do not prevent long sustained two-way conversation with high degree of intelligibility. The quality does not significantly degrade at 1.2 kbps and it is considered sufficient for messaging applications. 相似文献
8.
用二次插值实现近似弧长参数化 总被引:1,自引:0,他引:1
蔡放 《小型微型计算机系统》2000,21(4):445-447
分段二次Hermite插值用来保单调地反插值参数曲线的弧长函数.所作近似弧长参数化曲线在插值节点处,近似弧长是精确的,并且具有与精确弧长参数曲线同方向的单位切矢.在整个近似弧长参数区间,近似弧长的误差可达到0(△t)^2(△t为节点步长).数值实例得到了很好的结果. 相似文献
9.
参数曲线近似弧长参数化的插值方法 总被引:12,自引:1,他引:11
方逵 《计算机辅助设计与图形学学报》1996,8(2):115-120
本文提出了参数曲线近似弧长参数化的一种插值方法。参数曲线的弧长函数的单调增的,近似弧长参数化可以转化为弧长函数的保单调分段有理线性插值。用这种插值得到的近似弧长参数化曲线插值原曲线上的一组点,最后,两个实例表明了近似弧长参数化曲线能很好地逼近原曲线,且没有所不希望的波动。 相似文献
10.
11.
12.
基于误差控制的自适应3次B样条曲线插值 总被引:1,自引:0,他引:1
针对现有曲线插值算法不能有效压缩型值点的缺陷,研究了一种自适应三次B样条曲线插值算法。从型值点序列中选用最少的点插值一条初始曲线,基于提出的点到曲线的最小距离计算方法,分别计算各非插值点对应的插值误差,并从中提取最大插值误差。若最大误差大于给定的误差阈值,则将其对应的型值点加入插值型值点序列,重新插值曲线,直到最大插值误差满足误差要求。与现有曲线插值算法相比,该算法可以在保证插值精度的前提下有效压缩数据量。 相似文献
13.
提出了一种基于粗糙集约简的支持向量机图像插值方法,目的在于提高基于学习的插值方法的插值效率,改善放大图像边缘模糊现象。首先在原始图像上利用已知的像素灰度值及邻域内像素间的相关性构造训练样本集;然后利用粗糙集约简算法约简掉其中重要度较小的特征,并用约简后的样本集训练支持向量机;再用测试样本及训练好的支持向量机估计偶行偶列的像素灰度值;最后利用测试样本及训练好的支持向量机估计剩余的未知像素灰度值。仿真表明,所提方法有效提高了插值效率,获得了较好的客观指标,得到了满意的插值图像。 相似文献
14.
15.
基于三次样条函数的传感器特性曲面二维插值 总被引:7,自引:0,他引:7
在传感器输出、输入和环境参量均存在非线性的情况下,传统校准方法遇到困难,为提供一种提高测量精度的新途径,在接受非线性事实的基础上,采用三次样条函数二维插值,建立起传感器传递特性曲面.通过实例计算显示了一个化学传感器特性曲面.所获得的传感器特性曲面光滑性好,在输入和环境参量2个方向的一阶、二阶导数都连续,更符合传感器实际传递特性. 相似文献
16.
梁明 《电脑编程技巧与维护》2012,(8):4-5,7
介绍了CAD模型数据的检取技术和格式转换技术,描述了CAD/CAM的总体框架,并对实现该框架所涉及的内容及其实现技术进行了深入研究,同时给出了在Solidworks环境下所实现的CAD/CAM系统集成的实例。 相似文献
17.
Automatic Judgement on Form-Position Precision Grade of Features 总被引:1,自引:0,他引:1
Based on GB/T1184-1996, four form-position tolerance tables are listed on the appendix B. The regularity of distribution for form-position tolerances is deliberately analyzed. This paper describes a formulated method for identifying the precision grade, deduces the functional relation formulae between the tolerance and its precision grade, and further confirms the automatic judgement method presented by a practical program on PC computed 相似文献
18.
基于AIWCPSO算法的三次样条气动参数插值方法 总被引:1,自引:0,他引:1
针对飞行仿真建模过程中气动参数以矩阵的形式给出, 大都存在着非线性关系, 提出一种基于自适应惯性权重的混沌粒子群优化(AIWCPSO) 算法的三次样条气动参数插值方法. 首先建立粒子与三次样条插值函数中系数的映射关系; 然后利用AIWCPSO 算法对三次样条插值函数的系数进行寻优, 将获得的最优解近似看作三次样条插值函数的系数; 最后计算得到离散点的气动参数. 仿真实验结果表明, 所提出的方法能有效地解决飞行气动参数插值问题. 相似文献
19.
针对不完备决策表,黄兵给出一种基于容差关系的相容矩阵的属性约算法,但算法比较费时,其时间复杂度为[O(|C|3|U|2)]。为降低原算法的时间复杂度,以矩阵距离为启发信息,并运用矩阵合取的特性,设计了一个新的属性约简算法,算法时间复杂度降为[O(|C|2|U|2)]。通过实例验证了该算法。 相似文献
20.
基于线性插值填充的帧内运动补偿 总被引:1,自引:0,他引:1
帧内运动补偿被认为是H.264/AVC中具有潜力的改进方向之一。提出了一种线性插值填充算法来改进帧内运动补偿的编码效率。与Dong等人提出的自适应填充算法相比,线性插值填充能更精确地预测出填充区域内的像素,从而使得帧内运动补偿效率更高。实验测试表明,基于线性插值填充的改进算法可以使帧内运动补偿块数量增加4.58%~84.7%,从而令帧内编码的率失真性能得到提高。 相似文献