移动传感网中基于本地信息的机会路由策略

在考虑节点信道质量、移动方向和速率、剩余能耗等本地信息的基础上,在移动传感网中提出了基于本地信息的机会路由策略(OR LI)。该策略采用能在一定程度上反映信道质量的接收信号强度指示值对数 常态分布模型建立节点机会概率值;引入移动速率和方向反映节点的移动性;使用节点的剩余能耗反映节点的剩余使用寿命,实现机会路由,并通过候选节点的优选序号来确定候选点的侦听转发时间以避免报文重发。与机会路由策略ExOR和OB比,新策略更适合移动传感网,具有传输有效性高、能耗低等优点。     

基于均匀分布的机会网络消息转发策略

为了筛选出转发性能更优的中继节点,提高机会网络的消息投递成功率并减少消息传输时间,提出一种基于均匀分布的机会网络消息转发策略。该策略将携带消息的节点尽可能均匀地分布在网络中,使相同大小的空间内具有相同节点密度和携带消息节点个数,增大携带消息节点同目标节点相遇的概率。实验结果表明,与现有的消息转发策略相比,基于均匀分布的消息转发策略所需历史相遇数据较简单,算法复杂度低,对节点的缓存和能量要求不高,能有效改善机会网络的消息传输性能。     

机会移动传感网中基于感知方向的数据收集

机会移动传感网中数据收集策略既要保证传输成功率、减小网络开销,也要尽量降低传感器的能量消耗,从而延长网络生命期。遵循简单实用的原则,提出了基于方向感知的数据收集策略(Data Gathering based on Perceptive Direction,DGPD)。当两个传感器相遇时,以距离它们最近的Sink节点为参照点,分别计算各自的感知方向。把感知方向作为一个重要参数来确定两个相遇传感器的消息转发路由,把消息转发给更有利于接近Sink节点的传感器,从而提高数据收集成功率,减少过多的消息转发。模拟实验结果表明,这种策略可以有效地完成数据收集,并获得较高的网络性能。     

移动传感器网络中基于概率的数据传输策略*

移动传感器网络间歇连通,为了在拓扑动态变化的环境中将数据有效传递到汇聚点,提出了一种基于节点传输概率的数据传输策略PBD。该策略基于传感器节点近期与汇聚点的距离来计算节点将数据成功传递给汇聚点的可能性,并以此作为消息传输时选择下一跳的依据;同时还引入了基于消息优先权的缓存队列管理机制。实验结果证明了PBD的有效性,也表明PBD较好地实现了数据传输成功率与传输能耗、传输延迟之间的平衡。     

基于社区的机会网络中能量有效消息传输

针对机会网络中消息转发的特点,综合考虑节点移动的社区特性和能量有效传输策略,提出基于社区的能量有效消息转发算法（EEMF）,将节点的剩余能量与节点间的相遇概率作为消息是否转发的关键因素,并在社区内和社区间采取不同的消息转发策略,在提高消息传输成功率的同时,降低网络负载,减少节点能耗,延长网络的生命期。仿真实验结果表明,该算法与PRoPHET, MaxProp, CMTS, CMOT等经典算法相比,达到了预期的效果。     

动态传感器网络区域受限的移动sink路径选择研究

针对sink区域受限及节点特征参数的问题,如何规划sink路径选择以满足动态传感器网络高效数据收集及低能耗的要求,提出了一种动态传感器网络区域受限的移动sink路径选择方法。该方法在缓存节点辅助通信模式下,建立sink受限区域图模型。针对不同应用情况,分别讨论了sink移动全局路径信息已知和sink移动局部路径信息已知这两种情况下的最优移动路径。在全局路径信息已知时,采用Vornon单元划分的思想求解总传输能耗和节点平均负载;在局部路径信息已知时,采用启发式策略进行路径寻优,并证明其路径寻优的正确性。最后通过仿真实验与理论计算来验证移动sink最佳路径寻优策略的有效性和可行性。     

异构延迟容忍移动传感器网络中基于转发概率的数据传输

提出了一种基于转发概率的动态数据转发策略:FPAD(forwarding probability-based adaptive data deliveryalgorithm).FPAD适用于由不同类型传感器节点构成的可监测不同对象的异构延迟容忍移动传感器网络HDTMSN(heterogeneous delay tolerant mobile sensor network).在这种网络中,各类节点拥有不同的通信能力、运动速度与消息存储能力,并且获取的数据消息具有不同的大小和不同的延迟容忍度.针对异构网络的特点,FPAD一方面根据节点能量消耗和消息传输延迟计算出节点的传输概率和转发概率,并以此进行数据消息的传输;另一方面,提出根据消息当前的延迟容忍度作为消息丢弃依据的消息队列管理机制.仿真实验结果表明,与现有的几种数据传输算法相比,FPAD的数据传输成功率更高、传输延迟更小,而且网络寿命相对较长.     

VSR:多sink机会移动传感器网络的数据收集

机会移动传感器网络可应用在野生动物监控,或利用手持设备嵌入的传感器收集城市信息等场景,往往需要将数据从源节点传输到多个基站中的任一个.提出了一个基于虚拟空间的路由机制VSR(virtual space-based routing),采用"存储-携带-转发"的传输模式实现数据收集.每个传感器节点根据与多个sink节点的期望传输延迟映射成高维空间中的一个坐标点,消息传输对应于从源节点移动到空间原点的过程.细粒度的转发决策特性,使VSR自适应于网络的动态变化,具有很好的鲁棒性.此外,VSR机制具有很低的计算和存储开销,非常适合资源受限的传感器节点.两种不同随机特性场景下的模拟实验验证了VSR机制比ZebraNet的基于历史的转发机制和随机转发机制的性能更好.     

带移动sink节点的WSN节能路由算法

针对无线传感网移动路由算法中能量消耗大且消耗不均衡等问题,引入移动sink节点,提出一种带sink节点的WSN节能路由算法(MSEERP)。该算法基于网格思想来分割网络,根据节点的剩余能量和离簇重心距离的加权和选举簇头,避免了剩余能量低的节点被选为簇头;通过可控移动策略调度sink节点接收簇头所收集的数据,可以节省网络能耗。通过仿真,详细分析了sink节点的移动速度、移动sink节点的数量以及加权系数α对MSEERP算法性能的影响。分析结果显示,sink节点的移动速度为5、加权系数α为0.6且移动sink节点的数量为1时,MSEERP算法性能最佳;MSEERP算法在网络的生命周期、总能耗和sink节点接收数据量3个方面都优于GAF和TTDD算法。     

车载传感网中基于群特性的MaxProp路由协议改进

车载传感网中信息传输面临的主要难题是网络间歇性连通和拓扑高度动态变化,以往常常采用机会转发的思想设计路由协议来解决此难题。但现有的机会路由协议忽略了网络中部分车辆节点具有群组移动的特点,从而导致协议在群组移动场景下的性能急剧下降。为此,通过对最大相遇概率路由进行改进,提出了一种基于群特性的MaxProp路由协议。该协议利用群组内成员节点之间极好的连通性,通过群内消息扩散,间接提高群内节点与群外节点之间的相遇概率,从而增加了消息转发机会。并在ONE仿真平台上,与其他几种经典的机会路由协议相对比,改进后的MaxProp路由协议在消息传输成功率、网络开销比方面具有明显提升。     

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。     

基于QTE的蒙古文显示机制研究与实现

蒙古语言是中国蒙古族使用的通用语言,由于蒙古文区别于其他文字的书写方式和其自身变形机制等特点,在很多通用的文字处理引擎中都不被支持。在嵌入式产品开发与应用领域中Linux加QTE已经成为流行方式。该文给出了一种在QTE环境上实现基于标准Unicode的蒙古文点阵显示和变形算法, 并自定义了支持蒙古文的QTE组件,扩展了QTE功能,为在Linux加QTE方式的嵌入式体系结构中处理蒙古文提供了一种解决方法。