基于P2P网络的匿名通讯技术的研究与实现

P2P网络的应用给匿名通讯系统带来了可扩展性等优点,但同时P2P网络中节点的动态上下线又使得匿名通道缺乏稳定性.设计并实现了一种基于非结构化P2P网络的匿名通讯系统,称之为LeafageMix.与传统基于Mix网络的匿名通讯系统不同,该系统采用中继组的方式来建立匿名通道,使得匿名通道具有较强的抵抗节点失效能力,并提高了匿名通讯系统的实用性.     

CSP的扩展及其在匿名混淆协议形式化中的应用

自David Chaum在1981年提出了一个经过多个混淆器(Mix)的数据转发技术以来,匿名技术的研究得到了迅速的发展.研究为进行匿名混淆协议形式化描述而进行的CSP 扩展问题,向CSP 中引入了混淆操作的概念,提出了匿名混淆导管算子"⊕>>",该算子能够较好地描述匿名Mix混淆协议,最后给出了Mix混淆协议的CSP 描述.     

一种基于分组填充Mix策略的匿名通信机制

Mix机制为实现匿名通信技术提供了可行的解决方案,但攻击者仍可以在一定程度上通过流量分析来获取通信关系。为了进一步提高Mix机制对抗信息量分析攻击的能力,提出了分组填充的思想,并基于分组填充Mix策略给出了一种新型匿名通信机制。算法分析和仿真实验表明,与传统Mix机制相比,新的基于分组填充的Mix机制,能在有效抵御信息量分析攻击的同时,进一步降低网络的额外带宽开销。     

基于RGmix思想的匿名系统的设计与实现

Mix概念是当今许多匿名通信系统的基石,在现有的众多针对它的攻击方法中,(n-1)攻击是最强大的.本文设计并实现了一个对抗(n-1)攻击的匿名通信原型系统-RGmix,并通过实验进一步检验了RGmix思想的可行性.     

路网环境下位置隐私保护技术研究进展

基于位置服务(LBS)在给人们带来方便的同时也引起了越来越多的安全隐患,位置隐私保护成为了学术界和业界关注的焦点.由于大部分用户是沿着道路交通网络移动,研究路网环境下的位置隐私技术更具有现实意义.通过分析路网环境面临隐私泄露的新挑战,从网络扩张匿名技术、X-Star匿名技术、Mix zone匿名技术三个方面对现有路网下的位置隐私技术进行了深入研究,比较了其隐私水平、服务质量等性能指标.最后,总结了路网环境下位置隐私保护技术存在的问题及未来的研究热点.     

移动自组网匿名通信研究

本文概述了移动自组网络中匿名通信技术的研究意义和发展现状,讨论和分析了不同匿名方法的优缺点,并就将来此领域的发展趋势作了探讨。本文概述了移动自组网络中匿名通信技术的研究意义和发展现状,讨论和分析了不同匿名方法的优缺点,并就将来此领域的发展趋势作了探讨。     

高性能网包分类理论与算法综述

随着IP网络架构的不断演进以及网络业务和安全需求的不断增长,高性能网包分类在下一代交换机、路由器、防火墙等网络基础设备中有着越来越广的应用.网包分类算法作为高性能网包分类的核心技术,具有重要的研究价值和实践意义.文中从理论分析和算法设计两方面介绍了高性能网包分类的最新研究成果.在理论分析层面,依据计算几何理论对网包分类问题的数学解法及复杂度进行了归纳,总结了网包分类算法的理论依据及性能评价方法.在算法设计层面,对具有影响力的网包分类算法按照不同的研究方向进行了归类和介绍,并结合自身研究成果对不同类别的算法设计思路行了深入分析.作者在多核网络处理器平台以及FPGA平台上实现了几类具有代表性的网包分类算法,并通过真实的网络流量测试比较了不同类型算法在不同系统平台上的实际性能.最后,作者总结并展望了高性能网包分类的下一步发展方向.     

基于Petri网的非集中式电子商务平台建模与仿真

随着Internet的普及和网络安全性的提高,电子商务得到了迅速的发展.为了更好地满足网络环境下电子交易发展的需求,详细分析了电子商务的业务流程,设计了一个具有交易约束机制的电子商务系统框架.首先,基于Petri网这一建模分析工具,建立了电子商务系统业务流程的Petri模型,并设计了有界Petri网可达树生成算法,用于分析所设计的电子商务系统Petri网模型的性质;然后,运用Petri网系统动态仿真工具--CPNTools,对所设计的电子商务系统模型进行了仿真运行,并分析了实验结果.从静态和动态两个方面检验了所设计的电子商务平台框架的可行性,该框架可以用来指导下一步的系统开发工作.     

基于分布式爬虫的高性能Tor网络内容监控系统

随着网络的发展和普及,人们对于安全性、匿名性、反审查等信息安全的需求快速增强,越来越多的人开始关注和研究Tor匿名通信网络。目前针对Tor网络内容监控的研究工作大部分存在功能少、性能弱等劣势,如缺乏为暗网设计的专用爬虫,网络连接速度较慢,本文设计开发了一套综合性的Tor网络内容动态感知及情报采集系统,包含数据采集爬虫以及网页内容分类两个部分。其中爬虫部分使用了分布式架构,包括了任务管理模块、爬虫调度模块、网页下载模块、页面解析模块、数据存储模块,同时创新性地优化了Tor连接链路以提高爬取速度和稳定性;网页内容分类部分使用了自然语言处理技术,建立训练模型并对抓取到的信息进行精准高效分类,解决分类的准确度和复杂性问题,最后根据结果分析暗网的内容结构和敏感信息。我们也相应地为保障系统运行设计了容错模块和预警模块,从而对系统各个组件的当前状态进行实时监控,并将系统的状态数据进行整合、收集和展示。最后我们将该系统放到了实际Tor网络环境中进行了测试,从系统网页爬取效果、内容分类效果及系统性能等三方面进行了评估和分析,并与国内外7中现有的框架的功能进行了对比,证明本文提出的方案在暗网域名、网页、数...     

针对持续Mix的统计暴露攻击研究

暴露攻击是一种典型的针对匿名通信的攻击方式。基于统计暴露攻击的基本原理,针对持续发送的Mix机制,提出了一种基于数据包数量的统计暴露攻击算法, 测试并分析了目标节点接收者个数、系统中总的发送者个数、接收者个数以及Mix延迟对该算法攻击能力的影响。在此基础上,指出匿名系统可以通过发送者掩护和背景干扰的填充包发送策略来防范这种攻击。     

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.