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91.
为实现μs档条纹相机扫描非线性标定,建立了基于延时可调信号源和外触发激光器的条纹相机μs档扫描非线性标定系统,弥补了标准具法的不足。系统通过延时值的递增,得到条纹相机扫描速度在全扫程的变化。系统中时间关系抖动来源主要是测试设备延时抖动和条纹相机触发延时抖动。时间抖动测试与分析显示,条纹相机延时抖动±0.6ns,测试设备延时抖动±0.3ns,系统总时间抖动±0.7ns。系统时间抖动会造成最终时间轴信息的起伏。大量数值模拟分析表明,时间轴起伏对系统时间抖动的影响±2ns,在可以接受的范围内。因此,该系统能够胜任条纹相机μs扫程时间信息的测量标定。 相似文献
92.
Lienard系统的同宿轨族与闭轨族 总被引:4,自引:0,他引:4
本文讨论Lienard系统解的一些定性性质,得到了存在同宿轨族、闭轨族、双曲扇形和椭圆扇形、正负半轨有界及其与等倾线相交的充要条件或充分条件. 相似文献
93.
T. S. K. Moothathu 《Annals of the Institute of Statistical Mathematics》1985,37(1):473-479
Summary This paper presents the maximum likelihood estimators (MLEs) of the Lorenz curve and Gini index of the exponential distribution,
their exact distributions and moments. All these MLEs are shown to converge almost surely and in therth mean. Further their asymptotic distributions are obtained. Here we use only very simple arguments to derive certain results
that are very useful in statistical study of ‘inequality’. 相似文献
94.
95.
96.
Given a map f: X→Y and a Nielsen root class, there is a number associated to this root class, which is the minimal number of points among all
root classes which are H-related to the given one for all homotopies H of the map f. We show that for maps between closed surfaces it is possible to deform f such that all the Nielsen root classes have cardinality equal to the minimal number if and only if either N R[f]≤1, or N R[f]>1 and f satisfies the Wecken property. Here N R[f] denotes the Nielsen root number. The condition “f satisfies the Wecken property is known to be equivalent to |deg(f)|≤N R[f]/(1−χ(M
2)−χ(M
10/(1−χ(M
2)) for maps between closed orientable surfaces. In the case of nonorientable surfaces the condition is A(f)≤N R[f]/(1−χ(M
2)−χ(M
2)/(1−χ(M
2)). Also we construct, for each integer n≥3, an example of a map f: K
n
→N from an n-dimensionally connected complex of dimension n to an n-dimensional manifold such that we cannot deform f in a way that all the Nielsen root classes reach the minimal number of points at the same time. 相似文献
97.
Andreas Schweizer 《Transactions of the American Mathematical Society》2005,357(3):1047-1059
We study the extension generated by the -coordinates of the -torsion points of an elliptic curve over a function field of characteristic . If is a non-isotrivial elliptic surface in characteristic with a -torsion section, then for 11$"> our results imply restrictions on the genus, the gonality, and the -rank of the base curve , whereas for such a surface can be constructed over any base curve . We also describe explicitly all occurring in the cases where the surface is rational or or the base curve is rational, elliptic or hyperelliptic.
98.
M. L. Gorbachuk 《Functional Analysis and Its Applications》2005,39(1):71-75
We consider the equation Au = f, where A is a linear operator with compact inverse A
–1 in a separable Hilbert space . For the approximate solution u
n
of this equation by the least squares method in a coordinate system {e
k
}
k that is an orthonormal basis of eigenvectors of a self-adjoint operator B similar to A (
(B) =
(A)), we give a priori estimates for the asymptotic behavior of the expressions r
n
= u
n
– u and R
n
= Au
n
– f as n . A relationship between the order of smallness of these expressions and the degree of smoothness of u with respect to the operator B is established.__________Translated from Funktsional nyi Analiz i Ego Prilozheniya, Vol. 39, No. 1, pp. 85–90, 2005Original Russian Text Copyright © by M. L. GorbachukSupported by CRDF and Ukrainian Government Joint Grant UM1-2567-OD03.Translated by V. M. Volosov 相似文献
99.
Huang Zhaoyong 《代数通讯》2013,41(3):1457-1464
Let Λ be a left and right Noetherian ring. For a positive integer k, we give an equivalent condition that flat dimensions of the first k terms in the minimal injective resolution of Λ are less than or equal to k. In this case we show that the subcategory consisting of k-torsionfree modules is extension closed. Moreover we prove that for a Noetherian algebra every subcategory consisting of i-torsionfree modules is extension closed for any 1 ≤ i ≤ k if and only if every subcategory consisting of i-th syzygy modules is extension closed for any 1 ≤ i ≤ k. Our results generalize the main results in Auslander and Reiten [4]. 相似文献
100.
曲线拟合的广义最小一乘法 总被引:1,自引:0,他引:1
顾乐民 《数学的实践与认识》2011,41(19)
介绍了最小一乘法的方程式解法;讨论了这种方程式解法与最小一乘逼近之间的关系;说明了它不仅适用于线性函数类也适用于非线性函数类的最佳逼近的实现;提出了零偏差点附近数据变化的两个重要特征;建立了一种具有"人为"因素的广义最小一乘法;并给出了该法在预测方面的几个应用实例. 相似文献