恐怖袭击下危险品运输网络级联失效抗毁性建模与仿真

针对复杂网络的级联失效特性,提出了危险品运输网络在遭遇恐怖袭击后的级联失效抗毁性模型。在恐怖袭击条件下,对危险品运输网络的级联失效过程进行分析,定义了危险品运输网络抗毁性,从结果性和过程性两个视角出发,提出了网络抗毁性的评价测度节点存活率和相对二次级联失效数。通过建立仿真场景,给出了仿真流程图,并就不同节点的度、不同容量系数和不同规划方式下危险品运输网络级联失效特性进行了定量研究,并通过MATLAB软件编程实现。仿真结果表明了模型的科学有效性,为优化危险品运输网络的拓扑结构提供新的研究思路和方法。     

恐怖袭击下危险品运输网络抗毁性仿真分析

危险品运输网络在遭受恐怖袭击后单个节点的失效可能会引发网络级联失效现象。为解决该问题,构建一个危险品运输网络级联失效抗毁性模型。根据恐怖袭击条件,定义“正常”、“失效”和“暂停状态”3种节点状态,从“结果性”和“过程性”2个视角出发,提出网络抗毁性的评价测度。通过建立仿真场景,在不同节点的度、不同容量系数和不同规划方式下对危险品运输网络级联失效特性进行定量研究,结果证明了该级联失效抗毁性模型的科学有效性。     

蓄意攻击下一类多社团网络级联抗毁性研究

为研究社团结构对网络级联抗毁性的影响,结合一类多社团复杂网络模型,采用节点介数定义负荷,故障节点负荷采用局部择优分配策略,研究了在蓄意攻击下多社团网络负荷分配指数、社团内部耦合强度、社团间耦合强度、社团模块度等参数与级联抗毁性的关系。仿真结果表明负荷分配指数与级联抗毁性负相关,社团内部耦合强度、社团间耦合强度、社团模块度与级联抗毁性正相关。对比了BA(Barabási-Albert)网络和WS(Watts-Strogatz)网络的抗毁性,结果表明社团结构的存在降低了网络的抗毁性,负荷分配越均匀网络抗毁性越强。     

物流网络级联失效下的抗毁性分析

物流网络在突发事件下易发生级联失效现象,给网络的抗毁性带来巨大影响。针对物流网络中级联失效扩散机理的认知对于提高应急对策的有效性及控制效率具有重要意义。因此基于物流网络特征构建级联失效模型,分析研究级联失效的传播对物流网络抗毁性的影响。数值仿真结果表明：以物流中心为代表的II类中转型节点的失效对网络抗毁性的影响最大。物流节点间业务联系紧密程度及网络结构均对网络抗毁性产生重要影响。     

有向加权供应链网络级联失效的抗毁性研究

供应链网络是一个高度复杂的有向加权网络, 研究供应链网络本身的抗毁性对改良供应链网络拓扑结构, 提高网络稳定性和鲁棒性有着至关重要的意义. 因此本文依据复杂供应链网络中不同的网络攻击方式导致的节点 或者连边级联失效现象, 提出了一项在有向加权供应链网络下的抗毁性标准. 在提出的抗毁性准则中, 本文引入 了“网络运营度”的概念, 并针对有向加权网络的几种级联失效现象下的“网络运营度”的理论机理进行阐述, 最后 通过实验证明该抗毁性准则相对于其他文章所提出的抗毁性准则有着相对较好的表现, 证实了本文提出的抗毁性 测度的有效性.     

指挥控制网络级联失效建模与仿真

针对指挥控制网络拓扑结构以及级联失效等特点,以网络鲁棒性作为抗毁性测度,采用非线性负载容量模型和负载容量重新分配原则模拟级联失效过程,构建指挥控制网络级联失效模型。通过仿真分析负载参数、容量参数和演化步长等参量对指挥控制网络级联失效抗毁性的影响,为研究指挥控制网络的级联失效行为提供参考。     

城市交通网络的抗毁性研究

城市交通网络构成了一个典型的复杂网络。复杂网络的研究在过去几年得到了迅速发展,其中复杂网络的抗毁性是研究焦点之一。本文首先详细地介绍了当前复杂网络抗毁性研究的进展。最后,对考虑级联失效的城市交通网络抗毁性问题进行了讨论。     

基于节点修复的低轨卫星网络动态抗毁性模型

基于复杂网络理论,建立基于多智能体的低轨卫星网络动态抗毁性模型.完成低轨卫星网络的分布式拓扑结构的构建,将每个网络节点看成是一个具有自修复能力的agent,并在不完全信息条件下,采用一般性攻击策略研究信关站的分布、攻击强度、攻击力度、信息指数、自修复能力对低轨卫星网络抗毁性的影响.仿真结果表明:系统存在恢复时滞,对随机打击具有较强的鲁棒性,对蓄意打击脆弱性降低、稳定性提高,自修复性能弱化了网络的无标度特性;信息指数比攻击强度及攻击力度对网络抗毁性的影响更大;信关站分布对空间段网络抗毁性的影响较小,对地面段网络抗毁性影响较大,表明星际链路使得低轨卫星星座对地面网的依赖性大为降低.     

双层相依网络化指挥信息系统级联失效研究

网络化指挥信息系统是现代信息化条件下体系作战的基础支撑和重要枢纽.在分析网络化指挥信息系统结构功能基础上,构建带权重的双层相依网络,提出一种考虑节点过载和节点修复的级联失效模型,并在基于节点权重的负载重分配策略基础上构造基于节点相似、基于节点剩余容量和综合分配3种改进型策略.以“LB演习”数据为样本,针对攻击方式、负载重分配策略和网络性能参数对网络抗毁性影响展开研究.仿真结果表明:物理层重要节点对网络性能影响最为关键,并且网络性能会在蓄意攻击下产生突变现象;改进的3种策略,特别是综合分配策略,能够显著提升网络抗毁性,网络性能参数能够在一定范围内大幅提升网络抗毁性,避免大规模级联失效现象.     

指挥控制网络级联失效模型研究*

基于指挥控制网络的拓扑特征和级联失效特点,提出了一种带可调节参数的指挥控制网络级联失效模型。该模型提出了一种考虑节点组织地位的初始负载定义方法,以网络级联失效平均规模和级联失效临界值作为网络的抗毁性度量;通过仿真实验分析了网络负载的层次性、节点过载承受能力、跨级指挥和平行指挥等模型参数对指挥控制网络级联失效行为的影响,为现实指挥控制网络的级联失效行为的研究提供了新的思路。     

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.