基于解析-迭代重建的云存储密文优化检索

针对存储密文质量及加密性差所导致在检索时出现的检索效率低和检索不完整问题,提出一种基于解析-迭代重建的云存储密文优化检索的方法,首先将迭代重建与解析重建进行算法融合,构建出解析-迭代重建算法,并进行模拟映射,提升云存储密文的基础质量,然后使用神经元和Gauss分布状况构建奇偶树型交互学习机模型,并将遗传算法融入其中,通过混沌处理完成密文的优化,最后使用同态性密文检索算法对云存储内的文档划分,获取密文的大素数,再通过同态加密算法对文档加密,得到加密密文,这时根据大素数拟定随机数比对值完成云存储密文优化检索目的。仿真证明,所提方法能够有效加强密文质量,并具有检索效率高、完整性好的优点。     

四维混沌系统及其在图像加密中的应用

传统基于低维混沌系统的图像加密算法往往具有密钥空间较小、安全性较差的问题。针对这些问题,首先提出了一类新的平衡点不稳定的四维离散混沌系统,通过数值仿真对该类系统进行了动力学行为分析,正的Lyapunov指数的个数可以达到三个。同时并基于该类混沌系统设计了一个新的图像加密方案,并进一步对明密文的分布直方图、相关系数、信息熵以及加密方案对参数的敏感性进行了分析。分析结果表明,该加密方案抵抗外来攻击的能力强,密钥空间可达2996△,具有较高的安全性。     

一种基于广义混沌同步系统的图像加密方案

传统图像加密技术和低维混沌加密技术都有各自的局限性,而高维混沌映射比低维映射具有更复杂的动力学行为以及更好的随机性。在离散混沌广义同步定理的基础上构造了一种四维离散广义混沌同步系统,并设计了一种图像加密方案。 对加密图像进行了安全性测试,如分布直方图、相邻像素相关系数、密文信息熵、密钥敏感性、密钥空间和雪崩效应等。理论分析和数值实验表明,该加密方案的密钥空间达到10²⁸⁸,具有较强的抗攻击性能;对混沌系统参数及初始条件极其敏感,符合保密通信的要求。     

离散超混沌同步加密与流密码加密的比较研究

将离散混沌系统Dead-Beat同步方法应用于超混沌广义Henon映射,提出一种离散超混沌同步加密方案。该方案应用高复杂度的超混沌信号以增强载波信号的随机性,并利用了广义Henon映射Dead-Beat同步加密的复杂性。仿真结果显示:密文加密效果好,恢复图像与原图像差别很小。     

离散超混沌Dead-Beat同步加密方法的研究

该文将离散混沌系统Dead-Beat同步方法应用于超混沌广义Henon映射,提出一种离散超混沌同步加密方案。该方案应用超混沌信号以增强载波信号的随机性,并利用了广义Henon映射Dead-Beat同步加密的复杂性。尤其是发送、接收两部分同步的系统在硬件实现的情况下可以充分发挥混沌不可预测性的作用。因此,该文方案对于较高安全性加密系统的设计具有参考价值。仿真结果表明:密文加密效果好,恢复图像与原图像差别很小。     

二维反三角超混沌系统及其在图像加密上的应用

为了进一步提高混沌系统的混沌特性，为图像加密算法提供更可靠的混沌系统，增强图像加密算法的安全性，提出了一种基于二维反三角超混沌系统的新型图像加密算法。首先，在一维三角混沌函数的基础上构建了一个二维反三角超混沌系统，通过分岔图和Lyapunov指数等仿真实验，验证了该系统具有更广的混沌区间和更强随机性的迭代序列，遍历性更加优秀；然后，基于此混沌系统，采用"置乱-扩散"策略，根据不同密钥生成的不同超混沌序列，对图像矩阵进行无重复置乱和循环移位扩散，循环三次得到密文，完成加密过程；最后，对图像加密方案进行了直方图分析、密钥空间分析、相邻像素相关性分析、明文敏感性分析和信息熵分析等性能测试。其中密文图像的相关指标参数像素变化率（NPCR）和统一平均变化强度（UACI）的测试值非常接近于它们的理想期望值，信息熵的测试结果约为7.997，也非常接近于理想期望值8。实验结果表明，此图像加密系统具有更可靠的安全性，抵抗攻击能力强，在图像安全领域具有较好的应用前景。     

基于DataSocket技术的SMI敏感数据加密方法

由于以往加密方法是将所有的图像信息全部加密成密文图像,导致图像信息膨胀,影响了图像信息传输质量.为解决上述问题,研究一种基于DataSocket技术的序列监控图像敏感数据加密方法.方法先是序列监控图像敏感数据压缩处理,减少信息冗余度,具体包括图像分块、颜色空间转换、离散余弦变换、离散余弦变换系数量化以及编码等操作;然后利用混沌系统进行图像加密处理,包括实数混沌序列生成与转换、置乱和扩散等.实验结果表明:对比其它三种方法的加密结果,上述方法应用下信息熵最大,PSNR值较大,说明上述方法既能确保监控图像敏感信息安全,提高了图像的传输质量.     

基于L-K双混沌系统的彩色位级图像加密算法

针对传统加密算法精度有限、安全性低等问题,提出一种新的彩色图像加密算法。利用Liu混沌系统产生的混沌序列对彩色图像R、G、B三层的低五位进行索引位置置乱,再对高三位进行Arnold置乱;采用自适应方式进行扩散,并将R、G、B三层的密文图像循环异或,得到初步密文图像;联合像素级加密进行Hilbert置乱,采用Kawakami超混沌结合图像信息进行分形扩散,得到最终密文图像。仿真实验表明,该算法NPCR和UACI达到99.78%和33.37%,信息熵为7.9970,安全性很高。     

基于二维广义Logistic映射的图像加密算法

提出一个基于广义Logistic方程构造的二维混沌映射,采用Feigenbaum常数、相图、分岔图分析的方法,研究该混沌映射的非线性动态特性;然后利用该方程生成混沌序列,将混沌序列进行优化改进,生成密钥序列;最后采用输出反馈的加密方式,改变图像的像素值,达到加密的目的。实验仿真表明,该加密算法对密钥非常敏感,有效地提高了抵御选择明文攻击的能力,密文图像信息熵为7.996 94,非常接近理想值8。加密图像像素值具有类随机均匀分布特性,加密图像和明文图像之间的相关性非常接近于0,相邻像素具有零相关特性,而且密钥空间达到299比特。加密方法大大改变了明文图像的像素值,使得密文能够抵御统计攻击。     

参数扰动下的混沌的图像加密方案

针对计算机有限数字精度的限制导致混沌序列将退化为周期序列的缺陷,提出一种参数扰动下混沌的图像加密方案。首先,对已有的一个离散混沌系统进行了改进,得到了一个新的混沌系统。其次,将已有混沌系统的状态变量作为参数扰动,来扰动新构造的混沌系统以生成参数扰动下的混沌系统。在加密方案中,利用密文反馈的方式来控制迭代次数,动态产生密钥流。实验结果和安全性分析表明,该算法具有对密钥敏感、密钥空间大、密文图像统计特性良好、密文对明文敏感、能抵抗选择明(密)文的攻击等优点。     

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。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.