Exponential stability and exponential stabilization of singularly perturbed stochastic systems with time‐varying delay

In this paper, the problems of exponential stability and exponential stabilization for linear singularly perturbed stochastic systems with time‐varying delay are investigated. First, an appropriate Lyapunov functional is introduced to establish an improved delay‐dependent stability criterion. By applying free‐weighting matrix technique and by equivalently eliminating time‐varying delay through the idea of convex combination, a less conservative sufficient condition for exponential stability in mean square is obtained in terms of ε‐dependent linear matrix inequalities (LMIs). It is shown that if this set of LMIs for ε=0 are feasible then the system is exponentially stable in mean square for sufficiently small ε?0. Furthermore, it is shown that if a certain matrix variable in this set of LMIs is chosen to be a special form and the resulting LMIs are feasible for ε=0, then the system is ε‐uniformly exponentially stable for all sufficiently small ε?0. Based on the stability criteria, an ε‐independent state‐feedback controller that stabilizes the system for sufficiently small ε?0 is derived. Finally, numerical examples are presented, which show our results are effective and useful. Copyright © 2010 John Wiley & Sons, Ltd.     

Comparison of forecasting methods with an application to predicting excess equity premium

This paper reviews various forecast methods including combination using theoretically optimal weights and those under model selection approaches. In addition, we suggest two modified simple averaging forecast combination methods—a mean corrected and a mean and scale corrected method. We conclude that due to the fact that real data is usually subject to structural breaks, rolling forecasting scheme has a better performance than fixed window and continuously updating scheme. In addition, methods that use less information appear to perform better than methods using all the sample information about the covariance structure of the available forecasts. The mean and scale corrected simple average approach yield smaller mean squared forecast error than the three widely used regression approaches suggested by Granger and Ramanathan [11].     

多用户PHPWEB空间的安全策略

本文就多用户用的PHPWEB空间的安全问题作了全面的分析,并就操作系统和PHP环境及漏洞修补等方面给出了综合解决的完整方案。     

Noise-robust edge detector combining isotropic and anisotropic Gaussian kernels

A new noise-robust edge detector is proposed, which combines a small-scaled isotropic Gaussian kernel and large-scaled anisotropic Gaussian kernels (ANGKs) to obtain edge maps of images. Its main advantage is that noise reduction is attained while maintaining high edge resolution. From the ANGKs, anisotropic directional derivatives (ANDDs) are derived to capture the locally directional variation of an image. The ANDD-based edge strength map (ESM) is constructed. Its noise-robustness is determined by the scale alone and its edge resolution by the ratio of the scale to the anisotropic factor. Moreover, the edge stretch effect in anisotropic smoothing is revealed. The ANDD-based ESM and the gradient-based ESM with a small-scaled isotropic Gaussian kernel are fused into a noise-robust ESM with high edge resolution and little edge stretch. Embedding the fused ESM into the routine of Canny detector, a noise-robust edge detector is developed, which includes two additional modifications: contrast equalization and noise-dependent lower threshold. The aggregate test receiver-operating-characteristic (ROC) curves and the Pratt's Figure of Merit (FOM) are used to evaluate the proposed detector by abundant experiments. The experimental results show that the proposed detector can obtain high-quality edge maps for noise-free and noisy images.     

Segmentation of telecom customers based on customer value by decision tree model

The more the telecom services marketing paradigm evolves, the more important it becomes to retain high value customers. Traditional customer segmentation methods based on experience or ARPU (Average Revenue per User) consider neither customers’ future revenue nor the cost of servicing customers of different types. Therefore, it is very difficult to effectively identify high-value customers. In this paper, we propose a novel customer segmentation method based on customer lifecycle, which includes five decision models, i.e. current value, historic value, prediction of long-term value, credit and loyalty. Due to the difficulty of quantitative computation of long-term value, credit and loyalty, a decision tree method is used to extract important parameters related to long-term value, credit and loyalty. Then a judgments matrix formulated on the basis of characteristics of data and the experience of business experts is presented. Finally a simple and practical customer value evaluation system is built. This model is applied to telecom operators in a province in China and good accuracy is achieved.     

虚拟战场雷达频率及衰减强度可视化

雷达频率作为虚拟战场雷达作战信息可视化的重要内容,是战场可视化研究的重点。传统的雷达频率表现,主要通过建立光与频率的映射关系,利用颜色来进行表现,这种以光磁物理映射关系的表现方式在大规模虚拟战场表现上容易造成混乱,不利于区分不同类型信息。利用粒子法,将粒子跳动的速率与频率进行关联,在保证物理特性关联度的前提下,解放了颜色表现方式,同时利用射线和透明度法将雷达传播路径和衰减强度信息也进行了表现。     

文学艺术教育的人格修养功能

文学艺术教育在人格修养方面具有内涵的丰富性，层次的兼容性，方式的独特性。因此，文学艺术教育对人格修养方面起着可贵的辅助作用，它是思想道德课所代替不了的人格修养课程。     

爆炸冲击波作用下核电站安全壳动力分析模型

根据某国防科研课题，建立核电站安全壳在爆炸冲击波作用下的动力分析模型，讨论并分析了质点杆模型在安全壳预应力混凝土结构中的应用。质点杆模型可用于计算爆炸冲击波作用下的结构响应。     

离散时间Petri网的模糊模型

离散时间Petri网是一种系统模拟和分析的有效工具，它可以结合图形和分析描述评估离散事件系统的动态执行．基于T—S模糊模型，提出用于描述离散时间Petri网的模糊模型，讨论该模型适应于TtPNs的情况，用以推广文章结论，并且给出用于TtPNs的线性模糊控制规则．同时，文章还给出TtPNs聚合的结论．     

一种基于显微多光谱宫颈细胞图像自动分割方法

介绍了一种基于多光谱宫颈显微图像自动分割方法。细胞涂片每一个局部区域经过显微镜放大后再通过电调谐光器件分别取出不同光谱波段的图像，经过CCD送入计算机后得到该视场分析所需的多光谱图像。从所获得的多光谱图像中选择一定的波段图像对数变换相除、多阈值分割和形态学操作，最后获得宫颈细胞的胞浆和胞核覆盖层。本文首次将多光谱分析应用到宫颈显微图像分割中，具有分割准确、分割速度快、能够去除胞浆重叠和受外界干扰少的特点。