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61.
62.
D. Zwick 《Advances in Computational Mathematics》1994,2(4):375-391
We characterize the solution of the following problem and describe an algorithm for numerically solving it. Two sets ofN points in the plane, labeled 1,...,N, are given: a fixed set of nominal points and a set of measured points. We wish to transform the messured points as a whole,
by translation and rotation, so that the maximal distance between corresponding points in the two sets is minimized. This
algorthm provides an accept-reject criterion that may be used together with a coordinate measuring machine to determine if
two mating parts will fit, or if a part is sufficiently close to its ideal measurements. A weighted version, suitable for
point-dependent tolerances, is also discussed, as is optimal joint scalling of the data. 相似文献
63.
本文介绍高精度绝对式19-bit、21-bit光电轴角编码器的工作原理、具体结构、精度和可靠性等.采用移相电阻链细分和分段多次校正的方法对提高绝对式编码器的分辨率、精度和可靠性是有效的手段之一.检测结果:19-bit编码器的分辨率准确度σ=±0.6″ ,测角准确变σ=±1.2″;21-bit编码器的分辨率准确度σ=±0.2″,测角准确度,σ=±0.62″.其中,19-bit绝对式编码器早已用于光测设备中. 相似文献
64.
65.
Pisheng Ding 《Transactions of the American Mathematical Society》2006,358(9):3937-3967
Given a smooth closed -manifold , this article studies the extent to which certain numbers of the form are determined by the fixed-point set , where classifies the universal cover of , , is a polynomial in the Pontrjagin classes of , and is in the subalgebra of generated by . When , various vanishing theorems follow, giving obstructions to certain fixed-point-free actions. For example, if a fixed-point-free -action extends to an action by some semisimple compact Lie group , then . Similar vanishing results are obtained for spin manifolds admitting certain -actions.
66.
67.
In this paper, we determine the type numbers of the pseudo-hyperbolic Gauss maps of all oriented Lorentzian surfaces of constant mean and Gaussian curvatures and non-diagonalizable shape operator in the 3-dimensional anti-de Sitter space. Also, we investigate the behavior of type numbers of the pseudo-hyperbolic Gauss map along the parallel family of such oriented Lorentzian surfaces in the 3-dimensional anti-de Sitter space. Furthermore, we investigate the type number of the pseudo-hyperbolic Gauss map of one of Lorentzian hypersurfaces of B-scroll type in a general dimensional anti-de Sitter space. 相似文献
68.
Huaqing Sun 《Journal of Mathematical Analysis and Applications》2010,372(2):585-1850
This paper is concerned with the deficiency index problem of second-order differential equations with complex coefficients. It is known that this class of equations is classified into cases I, II, and III according to the number of linearly independent solutions in suitable weighted square integrable spaces. In this study, the original equation is reformulated into a new formally self-adjoint differential system by introducing a new spectral parameter and the relationship between the classifications of the equation and the system is obtained. Moreover, the exact dependence of cases II and III on the corresponding half planes is given and some criteria of the three cases are established. 相似文献
69.
记χ_(at)~e(C_n_i)为n_i阶的圈C_n_i的邻点可区别E-全色数.若n_i≡0(mod 2)(i=1,2,3…,t),则χ_(at)~e(C_n_1+C_n_2+…+C_n_t)=2t;若n_i≡0(mod 2)(i=1,2,3…,r,l相似文献
70.
MATHAI Varghese 《中国科学 数学(英文版)》2010,(3)
We review the Reidemeister, Ray-Singer’s analytic torsion and the Cheeger-Mller theorem. We describe the analytic torsion of the de Rham complex twisted by a flux form introduced by the current authors and recall its properties. We define a new twisted analytic torsion for the complex of invariant differential forms on the total space of a principal circle bundle twisted by an invariant flux form. We show that when the dimension is even, such a torsion is invariant under certain deformation of the metric and the flux form. Under T-duality which exchanges the topology of the bundle and the flux form and the radius of the circular fiber with its inverse, the twisted torsion of invariant forms are inverse to each other for any dimension. 相似文献