基于分簇的无线传感器网络密钥预分配方案

在无线网络传感器防止虚假攻击保证网络安全问题的研究中,针对无线传感器网络中的安全和提高系统识别认证能力问题,为了实现无线传感器网络中的安全通讯,需要对传感器节点间传递的信息进行加密.传统网络中使用的密钥分配策略,并不适用于无线传感器网络.分析了已有无线传感器网络密钥分配方案的特点.为了提高网络通信的安全性,尤其是在部分传感器节点被捕获后整个网络的健壮性,在分配方案基础上,采用一种分簇网络体系的密钥预分配方案.实验结果保证了连通率,节约存储空间,证明适用于现有的无线传感器网络.     

一种通过算法移植降低无线传感器网络能耗的方法

在研究了多种降低系统功耗方法的基础上,针对无线传感网络的低功耗要求,对无线传感器网络各模块进行了分析和研究,设计并实现了一种基于算法移植的软件开发低功耗的方法,有效降低了节点功耗.采用高性能无线传感器Imote 2节点进行实验,和原有方法进行了对比,并分析其功耗.结果表明:改进后的方法能有效地降低节点的能耗,延长了整个网络的生存期.     

无线传感器网络中一种分布式安全存储方案

对无线传感器网络的数据存储进行分析和研究,提出了一种以数据为中心的无线传感器网络中的分布式数据存储方案.该方案可有效解决集中式数据存储方案造成的中心节点的高负荷瓶颈问题,同时也避免了由于中心节点失效导致的数据丢失或泄漏问题.相对于现有的分布式数据存储方案,该方案运用Reed Solomon Code对数据进行加密,并且...     

基于安全连接的 WSN 节点优化部署

针对目前无线传感器网络节点覆盖优化方案中,无线传感器网络节点位置移动会破坏节点间的共享密钥的问题,采用了一种基于泰森多边形形心引力和存在共享密钥节点间的安全连接虚拟力的无线传感器网络部署方案.该方案以提高节点覆盖率为优化目标,引入安全连接虚拟力,以保证节点的安全连接;采用改进泰森多边形形心引力的虚拟力方案,能够有效指导节点散布过程和实现全局优化.通过仿真实验表明,本文方案能够提高节点的覆盖率,并且能够的减小存在共享密钥的安全连接的破坏.     

无线传感网中链路级能量有效策略的研究

无线传感器网络是一组带有无线收发装置的传感器节点组成的临时性的网络自治系统,由于无线传感器网络的节点是用有限寿命的电池来提供的,因此能量有效策略成为无线传感器网络研究的关键问题.由于传感节点的能耗主要集中在数据的接收和发送过程,因此研究传感节点之间链路级能量有效策略具有重要意义.主要针对链路级能量有效策略的研究,分析和总结了差错编码和低功耗调制的能量有效策略,提出了新的MAC层协议,并给出了OPNET仿真结果分析.     

无线传感器网络密钥分配方案改进与仿真研究

研究无线传感器网络安全中的密钥分配问题.由于传感器网络规模大、节点能源非常受限等特点,传统网络中使用的密钥分配策略并不适用于无线传感器网络.为了提高网络的安全性能,在预共享密钥和随机密钥分发方案的基础上,提出一种改进的随机密分配方案.首先通过传感节点的能量大小建立源传感节点到目的传感节点的多条传感节点不相交路径,然后根据传感节点的最小最大能量原理选择一条合适的传感节点不相交路径作为源传感节点和目的传感节点协商路径密钥的通道.仿真结果表明,改进后的方案保留了原方案的网络高安全性等优点,而且进一步节省了节点通信能量,延长了网络的生存周期,更加适用于能量非常受限的无线传感器网络.     

基于网络编码的ECC验证方案在WSN中的研究

网络编码在无线传感器网络应用,改善了无线传感器网络的性能.虽然与之前相比,其安全性有所提高,但当面临安全攻击(被动攻击和主动攻击)时,整个网络系统的安全性仍然亟待提高.提出了一种改进方案,该方案结合密码学中椭圆曲线加密箅法,并基于应用网络编码的无线传感器网络,采用加密验证方案.使传感器节点在电量受限的情况下,传输更多的有效数据.同时,增强了无线传感器网络节点之间通信的安全性,以及 WSN 其鲁棒性和容错性.     

无线传感器路由算法的应用研究

研究无线传感器路由算法,由于网络流量的突变性、时变性,传统无线传感器路由算法不能适应网络流量变化规律,导致网络信道竞争严重不公平、多边界问题和能量浪费严重,无线传感器网络生存时间过短.为了更好适应网络流量变化规律和有效延长网络生存时间,提出一种改进的无线传感器路由算法.算法首先对传统无线传感器路由算法退避机制进行改进,使信道竞争更加公平,以应对网络流量时变性,然后采用自适应占空比机制适合网络流量突发性,最后一个周期内同时发送多个数据组的调度方法,防止边界节点问题发生,从而使网络节省能量开销.在NS2仿真平台上进行了仿真,结果表明,改进S-MAC路由算法提高了网络平均吞吐量,使信道竞争更加公平,减少能量消耗,延长了网络生存时间.     

基于ZigBee的温室环境监测系统的设计

针对现有温室环境监测系统存在的不足,设计了一种基于ZigBee无线传感器网络的监测系统,通过软硬件相结合实现了温室环境数据的实时监测。硬件部分以CC2530为核心构建ZigBee无线传感器网络,包括传感器节点、汇聚节点;软件部分包括传感器节点的数据采集和发送、汇聚节点数据接收和发送、上位机监测管理3个部分。采用LabVIEW对上位机监测软件系统进行开发,人机交互界面友好。测试结果表明,该系统工作性能稳定,结构简单,布点灵活,可以实现温室内环境数据的无线监测。     

监测煤矿的一种无线传感器网络节点定位算法

利用DV-Hop算法实现了煤矿安全监测无线传感器网络节点之间的自定位.针对煤矿安全监测应用领域对网络节点定位的特殊要求,提出了一种节点定位精度的改进方案.介绍了引人距离误差校正值后的DV-Hop定位算法.该算法节点间通信量少,适合不均匀分布的网络场景.仿真结果表明:改进后的算法有效地提高了无线传感器网络节点的定位精度.     

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.