查询词典 best approximation

In this thesis, several optimization design problem in mechanical engineering are solved based on the best uniform approximation theory, and some initial work in the basic theory of the best uniform approximation is done.

本文应用最佳一致逼近理论，解决了机械工程中一些优化设计问题，并在最佳一致逼近问题的基础理论方面做了一些开创性的工作。

In the fourth chapter, firstly it introduces the Boolean functions algebraic expressions of the 2-value clock-controlled stop-and-go generator and Gunther generator. It reveals the balanced property of the two kinds of Boolean functions, and studies the Walsh cycle spectrum and the autocorrelation function. It also obtains the coincidence rate of their output sequences with affine sum of some bits of input sequences, and analyzes their ability of resisting the best affine approximation cryptanalysis and differential cryptanalysis. Secondly, we properly present a new definition of the Best Affine Approximation, namely BAA on the Boolean vector functions, followed by the spectral characteristic of such defined BAA attacks through using the decomposition formula of the union distribution for random variables. A lower bound of such BAA attacks is proposed. Finally, we also study the spectral characteristic of the second kind of nonlinearity of Boolean vector functions, followed by a higher bound of such nonlinearity. Furthermore, the limited relationship between the second kind of nonlinearity of Boolean vector functions and the linear structure of the linear combination of every component is analyzed.

在第四章中，首先给出了2值密钥流"停走生成器"和"衮特生成器"中实际存在的布尔函数的代数表示，揭示了这两类布尔函数的平衡性，随后研究了它们的Walsh循环谱和自相关函数等，得到了它们的输出序列与输入序列中的某些bit的仿射项的符合率，分析了它们抵抗最佳仿射逼近攻击和差分攻击的能力；其次，我们合理地给出了布尔向量函数最佳仿射逼近的新定义，利用布尔随机变量联合分布的分解式考察了相应的谱特征，并给出了布尔向量函数与其最佳仿射逼近的符合率的一个下界；最后，我们还考察了布尔向量函数第二类非线性度的谱特征，给出了布尔向量函数第二类非线性度的一个上界，并揭示了布尔向量函数第二类非线性度与其各个分量的线性和的线性结构之间存在的制约关系。

In this dissertation, the best simultaneous approximation with weight to infinite sequence from simultaneous-suns in complex normed linear space is considered, and in the case when the weight satisfies a certain condition, the characterizations of approximation from a simultaneous-sun and uniqueness of approximation from a RS-set are obtained; moreover, in the case when the weight is free, the characterizations of approximation to a totally bounded sequence from a convex set are established.

本文在复赋范空间中研究了同时太阳集对无限序列的加权同时逼近问题，在权满足一定条件时，通过把所研究问题转化为连续向量值函数空间中相应集对一个上半连续函数的最佳逼近问题，得到了逼近的特征和RS集逼近的唯一性定理，有例表明它们是已有结果的本质推广；在权不受限制时，得到了凸集对全有界序列逼近的特征。

In this paper, the elemntary knowledge of oblique circulant matrix is described briefly and three inverse eigenvalue problems which a-re denoted by Ⅰ,Ⅱ,Ⅲ and best approximation problem which is denoted byⅣ on oblique circulant matrix are presented.

本文介绍了斜循回方阵的基本内容，提出了斜循回方阵的特征值反问题Ⅰ，Ⅱ，Ⅲ及其最佳逼近问题Ⅳ，给出了它们有解的充分必要条件及求解算法，并举出了相应的数值例子。

In the product space of unanimity convex Hilbert, we obtained the theory of existence and uniqueness of best approximation element on weakly closed t convex set .

讨论了凸集及凸包的形态学运算的几个几何特性，并使某些文献中的几个错误结论得到修正和完善。

By the best approximation and the geometric interpretation of signal vectors in adaptive filters, the input noise variance is obtained with the information obtained from the traditional LMS algorithm. Then, based on γ-LMS algorithm, it can iteratively eliminate the input noise effects to obtain the bias in the Wiener solution and the true system coefficients.

根据自适应滤波器的最佳逼近原理和各信号矢量的几何关系，利用传统LMS算法获得的信息来估计输入噪声的功率，再通过γ-LMS算法在迭代过程中逐步修正维纳解，去除输入噪声的影响从而得到系统参数的真实估计。

A new type of polar decomposition—weighted polar decomposition of matrices is presented and defined. Aim at this new matrix decomposition, we prove its uniqueness theorem and obtain its uniqueness conditions, and also investigate the best approximation property of weighted unitary polar factor.

矩阵的极分解和广义极分解一直是矩阵分析研究的重要内容，本文中我们对其进行了横向扩展，提出并定义了一种新的极分解形式—矩阵的加权极分解。

These results are applied to solve a class of inverse eigenvalue problems for real matrices with a submatrix constraint and the expression of general solution and best approximation are also given.

最后，将所得的结果应用于子阵约束下实矩阵特征值反问题的最小二乘问题，得到了该问题解的表达式与最佳逼近解。

Finally, we prolongate the theory to two dimension tensor product wavelets space, proofing the best approximation property of product spline wavelets interpolation and constructing the parallel algorithm of the wavelets decomposition.

最后，我们继续将这一理论拓展到二维张量积小波空间，验证了乘积型样条小波插值的最佳逼近性质，进而在二维张量积小波空间构造了乘积型样条小波分解的并行算法。

The soupy mix is yak butter tea, or Bo cha, and the best approximation I can come to describing the taste is like a watered-down creamy corn soup with no corn. Not exactly what we have come to expect of 'tea'.

最后像汤似的成品就是所谓的酥油茶，至於酥油茶的味道，我能想到最接近的东西就是掺了水的奶油玉米汤，只是里面没有玉米，跟我们想像中的「茶」有些差别。

In the United States, chronic alcoholism and hepatitis C are the most common ones.

在美国，慢性酒精中毒，肝炎是最常见的。

If you have any questions, you can contact me anytime.

如果有任何问题，你可以随时联系我。