目标基视频编码中的运动目标提取与跟踪新算法

自动、快速的视频目标提取与跟踪是目标基视频编码中的一项关键技术.本文提出一种运动目标提取与跟踪新算法.首先,根据多帧运动信息和高阶统计检测方法得到二值运动掩模图像,然后提出一种改进分水岭算法对运动区域及其周围部分进行分割.将二者所得结果进行投影运算,得到最终运动目标.最后提出一种运动目标跟踪新算法,能对目标进行有效的跟踪.实验结果说明了本文算法的有效性.     

面向对象类测试方法分析

面向对象软件测试是面向对象软件开发的重要阶段，面向对象测试的关键是类测试，当前，类测试常用的方法是基于状态的测试和数据流测试，文章对这两种方法进行了分析和比较，提出了将来基于这两种方法的研究重点。     

CORBA分布对象计算方面的特性

网络技术的发展与面向对象技术的普遍采用促使了分布对象计算技术的产生和应用。文章简述了这一新技术的发展过程,对OMG的CORBA技术在分布对象计算方面的结构设计与对象管理进行分析,指出了它的优越特性和今后的发展趋势。     

PB封装WindowsAPI作图函数的方法

PowerBuilder是一种功能强大的数据库前端开发工具，然而PowerBuilder最大的缺点是作图功能不强，开发出来的界面不够美观。文中重点介绍用PowerBuilder中的不可视用户对象来封装WindowsAPI中的GDI作图函数来增强PowerBuilder的作图功能。     

Visual Basic中两种ADO数据库访问技术的比较

通过对VB中ADO控件和ADO对象模型访问数据库技术的比较,说明了VB中通过ADO访问数据库的机制。     

基于扩展客体层次结构的安全数据库策略模型

安全策略模型是安全可信系统的基础.Bell-LaPadula模型是多级安全系统中广泛应用的安全策略模型,但它缺乏针对数据模型的完整性和一致性规则.以该模型为基础,针对数据库系统的数据模型,提出了一个以扩展客体层次结构为基础的安全策略模型.模型通过扩展客体层次结构使完整性成为模型的内在属性,并引入或重新定义了客体域、扩展安全公理和操作规则.模型更加适应多级安全数据库系统的要求,增强了策略模型与系统规格和高层模型的一致性.普遍性和通用性安全模型的扩展和增强,特别是安全性以外的特性的引入是安全策略模型向实际系统模型转化的必要步骤.     

Obtaining complete 2 D view representation of polyhedra using concept of seedling single-view area

This article deals with construction of complete 2 D exact view models of polyhedral objects for visual identification systems. In particular, a new method and an algorithm views generation using the view sphere with perspective concept are described. A set of views generated by this method forms a complete view representation of the object. The method of ensuring completeness of the view representation by controlling covering of the view space (by single-view areas) is used in the presented algorithm. The perspective projection used for calculating the views, the total, tight covering of the view sphere by the single-view areas and -dimensionality of the views ensure, in our opinion, unambiguous and proper identification of polyhedral objects. The method consists in calculating single (any) view, determining the corresponding single-view area (so-called seedling single-view area) and then spiral propagation of neighbouring single-view areas until the whole view sphere is covered by them (i.e., until the border register containing the border between the covered and uncovered parts of the view sphere becomes empty). Having a complete set of single-view areas, we get a complete set of views as well. A method of determining single-view areas for convex polyhedra is also presented.     

Global stabilization and asymptotic tracking for a class of nonlinear systems by means of time‐varying feedback

A simple backstepping design scheme is proposed and sufficient conditions for non‐uniform in time global stabilization for parameterized systems by means of time‐varying feedback are established. Our methodology is applicable to a special class of systems that in general cannot be stabilized by static feedback and includes non‐holonomic systems in chained form. For this class of systems the main results on feedback stabilization enable us to derive sufficient conditions for the solvability of the tracking problem. Copyright © 2003 John Wiley & Sons, Ltd.     

Reliable Robust Preview Tracking Control Against Actuator Faults

In this paper we provide a solution to the reliable robust preview tracking problem against actuator faults for discrete LTI systems with polytopic uncertainties. This solution is in terms of the solvability of linear matrix inequalities (LMIs). The method is based on multi‐objective optimization and LQ tracking performance indices. To avoid the conservativeness problem associated with using a common LMI solution for the normal case and the fault cases, different LMI solutions are used in the proposed method. Two iterative algorithms are proposed and compared. Numerical examples are used to show the effectiveness of the algorithms.     

动态图像序列中的运动目标检测

根据动态图像序列中背景因成像过程中各种因素而产生变化所存在的复杂性，提出了自适应的前景目标检测方法。首先，建立图像每一像素点的高斯分布模型，并根据序列中的当前帧及历史帧信息自适应地调整模型的参数。然后，结合图像帧间的差分信息以及灰度分布的先验概率等因素将图像从空间域映射至统计域。最后，在统计域中对前景目标进行鲁棒分割。实验的结果反映了该方法的有效性。