共查询到20条相似文献,搜索用时 726 毫秒
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本文给出椭圆的焦点三角形与夹角有关的面积公式,并用分割法给出椭圆中与焦点有关的三角形的另一面积公式,然后通过类比不难得到圆锥曲线中其它相关结论,最后给出这些公式及变式的应用. 相似文献
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本刊1998年第8期《三角形特殊点的一般坐标公式》一文,介绍了三角形一些特殊点:内心、外心、重心、垂心、旁心和界心的一般坐标公式及求法.本文将给出一个点的坐标公式,用此坐标公式给出三角形特殊点坐标公式的统一求法.图1定理如图1所示,在平面直角坐标系下... 相似文献
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椭圆面积公式S=πab,其中π为圆周率,a、b分别是椭圆半短轴、半长轴的长.关于椭圆面积公式的证法有多种,文献[1]利用仿射变换与仿射不变量推导出椭圆面积公式,文献[2]通过对单位正方形的拉伸(压缩)变换前后面积关系的讨论,给出了椭圆面积公式的又一证法.文献[3]利用初等数学的方法,推导出椭圆面积的计算公式.本文利用投影和定积分知识相结合的方法,给出了任意曲边形面积公式,进而给出椭圆面积公式的一种新的证法. 相似文献
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We propose a random censorship model which permits uncertainty in the cause of death assessments for a subset of the subjects in a survival experiment. A nonparametric maximum likelihood approach and a “self-consistency” approach are considered. The solution sets corresponding to both approaches are found. They are infinite and identical. Only some of the solutions are consistent; i.e., the MLEs and self-consistent estimators are not consistent in general. Two estimates are thus proposed and their asymptotic properties are studied. It is shown that both estimates are strongly consistent and converge to Gaussian processes. The covariance structures of these Gaussian processes are derived. 相似文献
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Global depth, tangent depth and simplicial depths for classical and orthogonal regression are compared in examples, and properties that are useful for calculations are derived. The robustness of the maximum simplicial depth estimates is shown in examples. Algorithms for the calculation of depths for orthogonal regression are proposed, and tests for multiple regression are transferred to orthogonal regression. These tests are distribution free in the case of bivariate observations. For a particular test problem, the powers of tests that are based on simplicial depth and tangent depth are compared by simulations. 相似文献
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Janusz J. Charatonik Patricia Pellicer Covarrubias 《Proceedings of the American Mathematical Society》2002,130(7):2145-2154
Covering mappings on the dyadic solenoid are studied. Some results stated by Zhou Youcheng (2000) are discussed in a more detailed way by indicating certain inaccuracies in their proofs. These are either corrected or supplemented, or else suitable counterexamples are constructed. Some open questions are asked and connections with related results are considered.
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Ira M. Gessel 《Journal of Combinatorial Theory, Series A》2011,118(2):591-612
Point-determining graphs are graphs in which no two vertices have the same neighborhoods, co-point-determining graphs are those whose complements are point-determining, and bi-point-determining graphs are those both point-determining and co-point-determining. Bicolored point-determining graphs are point-determining graphs whose vertices are properly colored with white and black. We use the combinatorial theory of species to enumerate these graphs as well as the connected cases. 相似文献
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H. W. Corley 《Journal of Optimization Theory and Applications》1985,47(4):491-498
Two-person games are defined in which the payoffs are vectors. Necessary and sufficient conditions for optimal mixed strategies are developed, and examples are presented. 相似文献
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潘庆年 《数学物理学报(A辑)》2004,24(3):337-341
该文研究了(余)反射的等价性和可扩张性及应用,得到的主要结果如下:(1) 余反射余代数范畴和反射代数范畴是等价的.(2) 反射和余反射都具有可扩张性.使用这些结果可以用来推广和化简[1-4]中部分结论 相似文献
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Mengxin Wang 《随机分析与应用》2013,31(6):1107-1132
AbstractThis article is intended to study global asymptotical stability in probability for random impulsive coupled systems on networks with Markovian switching. Two cases are considered. (1) Continuous dynamics are stable while impulses are unstable; (2) impulses are stable while continuous dynamics are unstable. To begin with, based on Lyapunov method as well as graph-theoretic technique, several new stability criteria in two cases are derived, that are, the Lyapunov-type criteria and the coefficients-type criteria. Then main results are used for a class of random impulsive coupled oscillators. Finally, the effectiveness of the obtained results is verified by numerical simulations. 相似文献
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In the Vlasov–Maxwell theory we prove that there are homogeneous equilibria that are monotone decreasing in every direction and are arbitrarily close to a Maxwellian. They are unstable under certain electromagnetic perturbations, but are stable under purely electric perturbations as well as under electromagnetic perturbations of sufficiently short period. These statements are valid both in the linear and nonlinear senses. 相似文献