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．     

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.     

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。     

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。     

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．     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate