Demons非刚性配准算法拓扑保持性的研究

在基于配准的图像分割应用中, 拓扑保持性是非刚性图像配准算法的一个重要约束. 本文从矢量场特性出发, 分析了Demons非刚性图像配准算法导致目标拓扑改变时变形场的特点. 根据变形场特点与其雅可比行列式之间的关系, 给出了校正该算法拓扑保持性的方法. 实验表明, 改进后的变形场具有了拓扑保持性.     

Quantizer design for interconnected feedback control systems

In this paper, we consider the design of interconnected H-infinity feedback control systems with quantized signals. We assume that a decentralized static output feedback has been designed for an interconnected continuous-time LTI system so that the closed-loop system is stable and a desired H-infinity disturbance attenuation level is achieved, and that the subsystems’ measurement outputs are quantized before they are passed to the local controller. We propose a localoutput- dependent strategy for updating the quantizers’ parameters, so that the overall closed-loop system is asymptotically stable and achieves the same H-infinity disturbance attenuation level. Both the pre-designed controllers and the quantizers’ parameters are constructed in a decentralized manner, depending on local information.     

基于视觉伺服的自主微装配方法

研究基于视觉伺服的自主微装配方法,为实现深度信息估计,提出一种基于马尔可夫随机场的散焦特征参数模型,将散焦特征深度信息的估计转化为能量函数的优化问题,采用Broyden 图像雅可比矩阵实现视觉伺服控制。通过微夹钳自动定位与夹取实验,验证了该方法的有效性。     

基于ADL小波变换的图像压缩算法

提出一种基于自适应方向提升(ADL)小波变换的图像压缩算法。根据灰度共生矩阵角二阶矩的差异,将图像分割成平坦性不同的分块。对纹理信息较少的块,采用一般提升小波变换以减少变换时间。对纹理信息较多的块,采用方向提升小波以提高变换效果。结合多级树集合分裂编码和算术编码对变换系数和方向信息分别进行编码。实验结果表明,与ADL算法相比,该算法能有效减少方向小波变换时间。     

A local construction of the Smith normal form of a matrix polynomial

We present an algorithm for computing a Smith form with multipliers of a regular matrix polynomial over a field. This algorithm differs from previous ones in that it computes a local Smith form for each irreducible factor in the determinant separately and then combines them into a global Smith form, whereas other algorithms apply a sequence of unimodular row and column operations to the original matrix. The performance of the algorithm in exact arithmetic is reported for several test cases.     

Structure and reversibility of 2D hexagonal cellular automata

Cellular automata are used to model dynamical phenomena by focusing on their local behavior which depends on the neighboring cells in order to express their global behavior. The geometrical structure of the models suggests the algebraic structure of cellular automata. After modeling the dynamical phenomena, it is sometimes an important problem to be able to move backwards in order to understand it better. This is only possible if cellular automata is reversible. In this paper, 2D finite cellular automata defined by local rules based on hexagonal cell structure are studied. Rule matrix of the hexagonal finite cellular automaton is obtained. The rank of rule matrices representing the 2D hexagonal finite cellular automata via an algorithm is computed. It is a well known fact that determining the reversibility of a 2D cellular automata is a very difficult problem in general. Here, the reversibility problem of this family of 2D hexagonal cellular automata is also resolved completely.     

An alternative Kalman-Yakubovich-Popov lemma and some extensions

This paper introduces an alternative formulation of the Kalman-Yakubovich-Popov (KYP) Lemma, relating an infinite dimensional Frequency Domain Inequality (FDI) to a pair of finite dimensional Linear Matrix Inequalities (LMI). It is shown that this new formulation encompasses previous generalizations of the KYP Lemma which hold in the case the coefficient matrix of the FDI does not depend on frequency. In addition, it allows the coefficient matrix of the frequency domain inequality to vary affinely with the frequency parameter. One application of this results is illustrated in an example of computing upper bounds to the structured singular value with frequency-dependent scalings.     

The quantum query complexity of the determinant

In this paper we give tight quantum query complexity bounds of some important linear algebra problems. We prove Θ(n²) quantum query bounds for verify the determinant, rank, matrix inverse and the matrix power problem.     

基于非负矩阵分解的中文文本主题分类

提出基于非负矩阵分解（NMF）的中文文本主题分类方法,应用NMF算法分解词．文本矩阵获取词之间的相关性,有效地解决同义词、多义词的影响。实验结果表明,与基于奇异值分解的潜在语义索引方法相比,该方法计算速度快、占用存储空间较少。在潜在语义数据降低较大的情况下,NMF方法具有更好的分类精度。