个体差异对病毒传播效率的影响*

为了弥补传统病毒传播模型的缺陷,利用原胞自动机方法模拟了感染概率呈0-1分布、均匀分布、指数分布、幂律分布这四种情况下的病毒传播过程,结果发现当感染概率呈0-1分布时病毒的传播效率最高,而感染概率呈幂律分布时病毒的传播效率最低,这说明个体差异的存在能降低病毒传播的效率。该结论扩充了人们对病毒传播的认识,同时对真实系统的设计具有一定的参考价值。     

规则网络中的SIRS病毒局域控制建模与仿真*

提出一个带有局域控制的二维规则网络SIRS模型,理论分析和计算机仿真都表明局域控制能很好地抑制此模型中的病毒传播。研究发现系统状态随时间的演化最终会达到一个稳定状态;病毒的稳态感染比例与传播效率、被控制个体比例和免役个体失去免役能力的概率有关。只有当传播效率大于一个临界值时,病毒才能在网络中持续传播。     

稀疏网络中SIRS病毒局域控制模型与仿真

根据计算机病毒迅速传播所造成的重大危害,为了研究局域控制策略对稀疏网络中病毒传播的影响,提出了一个带有局域控制的二维规则稀疏网络SIRS模型。运行系统状态随时间的演化最终会达到一个稳定状态。发现病毒传播效率、网络中被控制个体比例、网络中个体密度和免疫个体失去免疫能力的概率这四个要素决定系统中病毒的稳态感染比例。只有当传播效率大于一个临界值时,病毒才能在网络中持续传播。采用计算机仿真和动力系统稳定性分析,仿真结果表明局域控制策略对控制稀疏网络中SIRS病毒传播有很好的效果。     

无线传感器网络的异质性对病毒传播的影响

病毒传播是无线传感器网络（Wireless Sensor Network, WSN）安全领域的一个重要问题。传统关于WSN中病毒传播的研究大多基于同质网络进行，很少考虑网络结构的异质性对病毒传播的影响。为了探究网络结构的异质性对WSN病毒传播效果的影响，分别从理论分析和仿真实验的角度对该问题进行了研究。首先，利用平均场理论建立了静态同质和异质WSN上的SIR病毒传播模型，计算得到了两种网络的传播阈值，结果显示，在网络规模足够大时，异质WSN的传播阈值等于0，而同质WSN的传播阈值大于0，且异质WSN的稳态感染比例要大于同质WSN，说明异质WSN更有利于病毒的传播。其次，对同质WSN 和异质WSN中的病毒传播过程进行了仿真，仿真结果与理论分析结果一致，仿真结果还显示，网络的异质性越高，越有利于病毒的传播。     

移动自组网病毒传播模型及稳定性分析

考虑移动自组网中节点的移动特性,基于平均场理论提出移动自组网中病毒传播模型,并对建立的方程组进行平衡点存在性和稳定性分析,得出病毒传播的阈值及消亡条件,从而研究节点移动速度、通信半径、免疫成功率和免疫失效率对移动自组网中病毒传播行为和传播临界特性的影响。结果表明:当病毒基本再生数R0<1时,网络全局渐近稳定在无病毒平衡点;当R0>1时,网络全局渐近稳定在地方病平衡点。最后通过数值仿真验证了该模型的正确性。     

PC Magazine安全建议

病毒档案病毒名称:911病毒(Worm.Neroma)警惕程度:★★★★发作时间:随机病毒类型:蠕虫病毒传播方式:邮件依赖系统:Windows 9X/NT/2000/XP感染对象:系统文件病毒介绍:该病毒会利用邮件进行传播,会向用户发送标题为:“It's Near 911!”(译文为:911快到了!),附件为:“911.jpg”的病毒文件。由于该病毒的邮件传播特性,当病毒传播时会导致系统资源和网络带宽被大量占用,影响企业与个人计算机的正常工作。病毒本身用VB高级语言进行编写,采用UPX格式压缩,因此兼容性好,传播速度快,能迅速渗透网络。运行时病毒会修改系统配置文件,在其中的自…     

基于异质移动网络的破坏性病毒传播模型

针对现有研究没有考虑移动网络节点异质性与没有构建破坏性病毒传播模型的问题,提出一个基于异质移动网络的破坏性病毒传播模型。通过考虑移动网络节点的异质性,进一步将易感染状态划分为新系统状态和旧系统状态,并结合破坏性病毒的潜伏与爆发特性将感染状态划分为潜伏状态和爆发状态。计算了模型的平衡点与传播阈值,并指出当传播阈值大于1时,模型在正平衡点处不稳定;当传播阈值小于1时,模型在正平衡点处局部渐近稳定。在NW小世界网络和BA无标度网络上进行仿真对比实验,仿真结果表明,两个网络的病毒传播速度不同,NW网络存在病毒完全消除的情况,而BA网络中的病毒不会被完全清除。     

无标度网络上带人工免疫的SIRS模型的动力学行为及其免疫控制策略

在典型的SIRS模型的基础上,提出了一种无标度网络中带人工免疫的SIRS类传染病模型.运用平均场理论方法分析了所提模型的动力学行为,研究了在两种不同的人工免疫策略下病毒在一种特定的无标度网络上的传播情况,并模拟了两种免疫策略对病毒传播的影响.模拟结果表明,通过人工免疫可以有效降低稳态感染比例,提高系统的传播阈值,从而有效控制病毒在复杂网络上的传播.     

风险意识加强的自适应网络病毒传播研究

当疾病在人群中爆发时,人们对病毒传播的风险意识和规避行为随着人群中感染密度等因素的变化而作自适应的调整.针对人群中不断变化的风险意识和规避行为,提出在SIS网络传播模型中,用时变重连概率函数描述该变化过程,研究自适应网络的动态传播过程.结果证明,网络中时变重连函数的稳定值大,则病毒传播规模小.时变重连概率函数增长速度快,则病毒传播速度慢.表明人们的风险意识高且规避措施全面时,病毒最终的传染规模也小,同时,能及早地认识病毒的危害并采取规避措施,有利于对病毒传播的抑制.     

PC Magazine安全建议

病毒档案病毒排行榜病毒名称:泡沫人(Worm.p2p.fizzer)警惕程度:★★★★发作时间:随机病毒类型:蠕虫病毒传播方式:邮件/P2P系统依赖系统:WIN9X/NT/2000/XP感染对象:邮件病毒介绍:该病毒利用P2P和邮件系统进行网络传播,病毒运行时会记录用户计算机内的个人信息,发送到指定信箱,并按用户地址簿向外疯狂发送病毒邮件,从而导致网络阻塞和用户信息被泄露。病毒的发现与清除:此病毒会有如下特征,如果用户发现计算机中有这些特征,则很有可能中了此病毒,可以按照下面所说的方法手工清除“泡沫人(worm.p2p.fizzer)”病毒。1. 该病毒会在WIND…     

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。     

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.     

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.     

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.