一种新的混沌伪随机序列生成方法*

针对单混沌系统因计算机有限精度效应产生的混沌退化问题,提出了一种多级混沌映射交替变参数的伪随机序列产生方法。该方法基于一维Logistic映射和二维Henon映射,用交错变参的Logistic映射的混沌迭代值的汉明重量来控制Henon映射输出的混沌迭代分量。生成序列通过仿真表明,符合Golomb三个随机性公设要求及局部随机性统计检验要求,可作为密钥流序列应用到加密体制中。     

飞轮调速器反馈控制系统的混沌及控制

建立了飞轮调速器反馈控制系统的动力学方程,利用系统的相图和Poincar6映射图分析了系统的混沌形成过程．通过对飞轮调速器反馈控制系统增加一个比例微分反馈控制器,利用它控制系统从混沌运动转化为周期运动．数值仿真表明了该控制方法在飞轮调速器反馈控制系统的混沌控制中的有效性与可行性,可利用适当的控制强度镇定系统中不稳定的周期轨道．     

一种新型Skew Tent映射的混沌混合优化算法

针对已有的混沌优化算法几乎都是利用Logistic映射作为混沌序列发生器,而该混沌序列的概率密度函数呈两头多、中间少的切比雪夫型的分布性质,不利于搜索的效率和能力,为此,首先构造一种新型混沌映射序列发生器—Skew Tent映射并结合迭代优化特点加以改进,然后分析了它的混沌特性．其次,将改进的混沌映射与Alopex启发算法相结合,充分发挥Alopex算法的快速搜索能力和混沌优化全局寻优的特性,提出一种混沌混合优化算法,提高了算法的收敛速度和有效搜索全局最优解．最后,仿真算例验证了该算法的有效性和Skew Tent混沌映射的应用前景．     

混沌态电流模式Buck-Boost开关变换器的OGY控制

从电流模式Buck-Boost开关变换器周期 1状态的频闪采样离散时间迭代映射数学模型出发，提出了一种混沌态电流模式Buck-Boost开关变换器吸引子中不稳定周期 1轨道的确定方法．根据OGY控制的原理和思想，推导出OGY控制矢量的取值范围，以此为依据选择控制矢量，实现了对混沌态的电流模式Buck-Boost开关变换器相空间中的一条不稳定周期 1轨道的稳定控制．     

基于复合混沌系统的数字图像加密方法研究

分析了现有图像加密方法的安全性,提出了一种改进的图像加密方法,将两套Logistic映射组合起来构成参数变化的双Logistic映射复合混沌系统,系统中的Logistic映射相互控制对方的μ参数,并产生两个混沌序列。然后用其中一个混沌序列对图像矩阵进行置乱,另一个混沌序列用于对图像信息进行异或加密。计算机仿真结果表明,该加密方法具有良好的加密效果,具有可行性,算法实现简洁,有较强的抗攻击和抗噪声能力。     

参数自适应控制的混沌同步研究

在对同步系统特性分析的基础上,利用参数自适应控制混沌原理,提出了一种混沌系统在不同系统参数下的混沌同步方法.在参数自适应控制方程中,采用了分段控制与非线性反馈控制相结合的控制函数.通过选取合适的控制律和控制参数可以实现不同系统参数的两个 logistic映射的混沌同步.基于 Matlab软件的数值仿真的结果表明该方法是控制离散混沌系统同步化的一种快速有效的方法.     

混沌PSO分析及其在船舶设计中的应用

分析了不同混沌序列的数值分布特点,凭借其良好的对可行域的遍历性质,将混沌映射引入粒子群优化算法当中,应用混沌粒子群求解有约束优化问题。在分析了约束条件性质的基础上,提出通过控制约束条件进而控制可行域的主要分量以提高混沌粒子群的搜索效率,并借助于混沌映射的遍历性解决部分非关键条件未被采用的问题。通过对标准测试函数的数值实验表明,基于改进tent映射和logistic映射的混沌粒子群在计算时间与搜索效率上与基本粒子群相比具有较大优势。将改进的混沌粒子群应用于某内河双桨船型的主尺度决策中,通过对最佳船型要素的多次搜索测试表明,此方法的搜索可靠性较高。     

基于自适应神经网络的不确定混沌系统控制

针对不确定非线性混沌系统,提出一种基于动态神经网络建模的控制新方法.基于Lyapunov稳定性理论,推导出了神经网络权值在线学习规律,保证了系统的全局稳定性.在混沌建模阶段,神经网络用于学习不确定混沌系统,然后在所建模型的基础上,设计控制器将混沌状态引导到期望目标位置;并且对系统的稳定性能进行了严格的数学分析.把该方法应用到Logistic映射和Hénon 映射建模和控制,数值仿真表明该方法的有效性.     

图文混沌加密在互联网传输的多格式处理与识别

混沌映射便于产生具有混沌特性的序列,这一特性为将混沌保密通信技术应用于互联网的加解密提供了很大的便利．根据混沌映射的这种特性,探讨了在图文多格式条件下,如何实现利用混沌映射产生的流密码对图文加解密,确保计算机对解密后的图文能进行正确识别和显示．文中方法克服了只针对单一图文格式进行加解密的局限性,使得它具有很强的实用性．     

元模型误差导致的仿真过程不可重现性研究

混沌动力学系统内在的不可预测性限制了元模型技术的应用。分析了元模型重现原始模型输入/输出映射关系的基本特性,以及混沌动力学系统采用元模型技术时内在的不可重现性;为使元模型能够重现混沌动力学系统的输入/输出映射关系,提出了控制原始模型运行特征和控制元模型输出参数误差2种控制策略;最后针对逻辑斯蒂映射混沌动力学系统,研究了2种元模型构建控制策略的具体应用。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。