Hadoop平台下基于优化X-means算法的大数据聚类研究

针对WSNs中现有路由算法存在的各种不足,本文提出了一种基于占空比间隔优化的延迟约束路由算法。具体来说,在提出的算法中,首先,将端到端延迟分布估计为占空比间隔和潜在转发器数量的函数,在给定的网络模型和参数下,其分布可以近似地估计。然后,选择满足延迟约束成功率(Delay-Constrained Success Ratio,DCSR)要求的占空比间隔最大值,每个节点独立地调度其休眠和唤醒时间,发送端节点将数据包转发给潜在转发器中最先唤醒的节点,从而确保数据包以要求的概率即DCSR到达接收器,同时最大化占空比间隔；仿真实验结果表明,提出的路由算法不仅能够满足要求的DSCR,并在ETE延迟、数据包交付率和实际得到的DCSR方面都优于现有的先进算法。     

基于报文检测的快速自适应NoC容错路由算法

传统的自适应片上网络(NoC)容错路由算法采用一步一比较的方式来确定最优端口, 未能有效降低传输延迟。根据数据包在2D Mesh NoC前若干连续的跳数内最优端口固定的特点, 提出了一种基于报文检测的快速(FPIB)自适应容错路由算法。算法采用跳步比较的方式来减少数据包的路由时间, 并使用模糊优先级策略来进行容错路由计算。实验结果表明, 与uLBDR容错路由算法相比, 该算法能有效地降低平均延迟, 且实现算法的硬件开销更低。     

能量均衡的ZigBee路由算法优化研究

传统的ZigBee路由算法存在泛洪式路由请求(Routing Request, RREQ)消耗网络大量能量和网络内节点能耗不均等问题,缩短了网络生存周期。本文提出一种优化选取转发节点的能量均衡路由算法。在路由发现阶段限制RREQ广播半径,路由选择阶段通过多目标优化选取最佳下一跳节点,并且通过节点间周期性交换休眠时序,实现同步低功耗路由机制。基于NS-2.35的实验结果表明,与传统的ZigBee路由算法相比,本算法可以提高数据包的平均到达率,减少数据包的平均端到端延迟和保持网络内节点能量平衡,进而延长网络生存时间。     

基于Iptables和Linux策略路由的防火墙实现

策略路由是目前硬件路由器支持的一种高级路由技术,路由器不仅可以根据目的IP地址进行路由选择外,而且还可以根据其他因素进行路由选择。在Linux下应用iptables和策略路由实现防火墙,在功能上更强大,使管理员更灵活方便的控制所需要的转发,不仅能够根据IP包的目的地址而且能够根据报文大小或IP源地址来选择数据包的转发路径,以更好的控制内外网数据包的转发和限制。     

基于历史效用的机会网络路由算法

针对机会网络中传统的概率路由协议投递率较低的问题,提出一种基于历史相遇预测的改进概率路由(HMPR)算法。该算法根据节点历史接触时间和接触频率两个因素,预测数据包成功投递到目的节点的效用值,通过比较其效用值大小来决定数据包是否转发到下一跳节点。仿真结果表明,与传统的传染路由和概率路由相比,该路由在数据包投递率、平均延迟时间和平均缓存时间方面比上述两个路由协议的性能更好。     

骨干无线网状网的排队延迟性能研究

对一种基于网状分布的骨干无线网状网的延迟性能进行研究.提出了一种基于均衡负载的最短路径路由协议.在此协议基础上,研究了无线网状网数据包的排队延迟,推导出无线网状网排队延迟与网络的规模、网关和网状路由器的服务能力、数据包到达率的相互关系.此外,还分析排队延迟和网络容量的相互制约关系,并给出了在延迟限制条件下的网络容量.     

基于GTNetS的蠕虫模拟路由策略的改进

蠕虫模拟时产生的无效IP地址扫描包会在源节点所属的路由器被直接丢弃,这与实际网络中数据包的传输情况差距较大。该文针对这一问题提出改进路由策略的方法,并实现对模拟器GTNetS路由策略的修改。为量化改进路由策略前后的区别,给出一个理想的假设模型,并进行模拟实验。实验结果与模型的理论值相符,改进路由策略后能够更准确地反映蠕虫数据包在网络中的传输。     

基于混合策略的动态多跳无线网络路由算法

针对动态多跳无线网络中节点的动态变化和数据包的转发冗余问题,提出了一种基于MPR (multipoint relays)和评价函数的混合动态路由策略.确定节点的MPR集,并基于评价函数对MPR集中的节点排序.无线通信时,节点根据本地存储的MPR集将数据包转发给传递成功率高的节点,若MPR中没有可成功转发节点的信息,则随机选择MPR集外的节点,定向转发与随机转发相补充使数据包能在较短的时间内准确的到达目的节点.仿真结果表明,该路由策略能有效的降低平均时延和丢包率,提高了传输率.     

网络时延在线估计技术与控制器的协同设计

通过在数据包中附加路由信息, 利用路由跟踪的策略, 确定数据包到达目标节点所经过的路由器的数量, 以此给出网络诱导时延的在线估计方法, 从而较好地克服了利用时间戳方法测量网络传输时延时所产生的远程节点与本地节点之间的时间同步问题. 通过对引入的数据包路由信息的设置和网络路由瓶颈的分析, 给出数据包传输周期的下确界和一种简单的数据丢包的判别方法. 最后给出控制器的协同设计步骤, 实验研究验证了本文方法的有效性.     

基于UDP传输协议的包丢失和失序处理

UDP是互联网上多媒体数据传输采用的主要传输协议。其主要特点是网络开销低但传输不可靠,易产生包丢失或失序。为了对失序数据包进行重排序,应用程序需要预留一个适当的缓冲区以存储期望包到达之前的数据包。该文分析了数据包丢失或失序情况下,缓冲区大小对系统性能的影响,给出了缓冲区大小的一个估计值,并对失序或数据包丢失情况下数据处理的策略进行了讨论。     

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.