基于有机分子亚铁磁体棱型自旋链外场下的热力学性质研究

基于近来有机高分子亚铁磁体在试验上成功的合成，本文采用量子转移矩阵方法，研究一维反铁磁-铁磁自旋1／2棱型自旋链在外场条件下低温下的热力学性质．磁化强度在低温下随外场的变化出现台阶式的平台结构，并表现出三个临界外场值，反映了系统磁相互耦合作用与热力学波动间的相互竞争；同时磁化率在外场下呈现双峰结构，其来源于系统在外场下的能隙和长程序参量的变化．本文的数值结果表明该棱型链与自旋1-1／2海森堡链性质一致．     

不可约符号矩阵的广义基指数的上界的可达性证明

给出了本原符号矩阵的广义基指数达到最大值时的极矩阵刻画,并证明了邵、尤给出的非本原不可约符号矩阵的广义基指数的上界是最好的.     

基于灰度和梯度不变矩的人脸识别

提出一种新的人脸识别方法———灰度-梯度共轭不变矩法,克服了传统方法的缺点,在不增加复杂度的前提下,将灰度信息和梯度信息有效地结合起来,并将其共轭分布反映的纹理特征作为对灰度特征的补充参与特征分类.同时,对经典不变矩组进行分析并改进,消除了离散状态下比例因子的影响.以BP网络作为分类器进行试验,结果表明,与传统方法相比,该方法具有更高的识别率.     

行(或列)对称矩阵的Moore-Penrose逆

证明了行(或列)对称矩阵的Moore-Penrose逆与母矩阵的Moore-Penrose逆的定量关系,给出了两种快速算法。据此可大大降低一类具有该结构矩阵的Moore-Penrose逆的计算量和存储量。     

基于观测器的时滞依赖鲁棒无源控制

研究一类带有参数不确定性和时变时滞的不确定线性系统的鲁棒无源控制问题。针对标称系统,利用线性矩阵不等式给出其时滞依赖无源性条件;讨论当系统的系数矩阵出现参数不确定时,存在基于观测器的控制器使得闭环系统是强鲁棒稳定且严格无源的时滞依赖性充分条件。构造出期望的观测器和控制器。数值算例说明结论的有效性。     

Design of Luenberger function observer with disturbance decoupling for matrix second-order linear systems-a parametric approach

1.INTRODUCTIONThere have been many approaches to disturbance de-couplinginlinear multivariable control systemdesign.Linnemann[1]proposed a numerically stable algorithmfor disturbance decoupling by measurement feedback.Van Der Woude[2]considered the combined problemof disturbance decoupling and stabilization by mea-surement feedback.Syrmos[3]proposed a numericallyefficient algorithm based on Sylvester equations forthe problemof disturbance decoupling with arbitrarypole placement usingstat…     

Distribution-based CFAR detectors in SAR images

1. INTRODUCTION Many researches have been made on automatic target recognition (ATR) from SAR images in the past few years. Lincoln Laboratory has developed a complete, end-to-end ATR system[1-4]. The whole system inclu- des three stages: detection (or prescreening), discri- mination and classification. In the detection stage, a two-parameter CFAR (constant false alarm rate) detector is used as a prescreener to select candidate targets in an SAR image on the basis of local brightne…     

Decentralized robust stabilization of discrete-time fuzzy large-scale systems with parametric uncertainties: a LMI method

1. INTRODUCTION Large-scale dynamic system theory has been intensi- vely studied during the past decade[1～3], but for fuzzy large-scale systems, namely large-scale systems comp- osed of a series of fuzzy subsystems, has been seldom done in literature. In Ref.[4], decentralized stabiliz- ation problem of fuzzy large-scale systems composed of a series of fuzzy subsystems was considered. Sufficient conditions for asymptotic stability of the fuzzy large-scale system and design methods of dec…     

几类对角占优矩阵的Hadamard积的性质

得到了几类对角占优矩阵的Hadamard积及Hadamard方的一些性质.     

广义Hermite逼近及基于广义Hermite多项式变换的实现

讨论了利用广义的Hermite多项式作为基函数的谱方法的逼近性质.和古典的Hermite多项式相比,广义的Hermite多项式具有更好的逼近属性和更灵活的适应性.并推导了相应的广义Hermite多项式变换.利用广义Hermite多项式变换可以有效地实现广义的Hermite多项式逼近.数值试验进一步验证了理论的正确性.