基于期望寿命的能量均衡RPL研究

目前基于能量均衡的低功耗有损网络路由协议RPL (Routing Protocol for Low power and lossy networks)在网络拓扑构建的过程中由于未考虑备选父节点上一跳节点的期望寿命,从而导致所构建的网络不能较好地实现能量均衡的问题。对此提出一种基于期望寿命的能量均衡RPL(Expected Life Time-based Energy Balance RPL, ELT-EB-RPL)。构造一种复合路由判据,包括传输跳数、期望传输次数和节点期望寿命,同时,节点在选择最优父节点时需综合考虑其备选父节点及备选父节点上一跳节点的期望寿命。在不增加额外控制开销的前提下,提出一种"节点间期望寿命信息通告"策略,以便节点作出正确的路由选择。通过仿真实验对该方案的性能进行了对比分析。结果表明,在不同发包速率下该方案能够有效实现能量均衡和延长网络寿命。     

能量均衡的低功耗有损网络路由协议

针对目前低功耗有损网络路由协议（RPL）中存在节点能耗不均衡、网络生存时间短以及网络后期父节点状态信息更新不及时的问题,提出一种带有电量估算策略的能量均衡RPL（EB-RPL）。首先,构造了一种复合期望传输次数和节点剩余能量的路由度量,通过机制设计使节点在不同时期能自适应地调整网络拓扑;然后,设计了一种基于能量消耗速率的父节点电量估算策略,在不增加额外控制包开销的同时,子节点可以计算父节点电量,作出正确的路由决策;最后,通过实验对比分析了EB-RPL的性能。仿真结果显示,与RPL相比,EB-RPL显著降低了同级节点间功率标准差,并且在不同发包频率和网络规模中,分别平均延长了29.4%和39.4%的平均网络生存时间。EB-RPL能够有效实现能量均衡、显著延长网络生存时间。     

基于置信区域设置的低功耗有损网络路由

现有多数低功耗有损网络路由(RPL)协议没有考虑真实环境中移动节点的定位误差。为此,提出基于移动节点置信区域的低功耗有损路由协议,记为KPRPL。KPRPL协议考虑了静态和移动两类节点,并正视真实环境下的定位误差。在静态节点间路由,KPRPL协议考虑传统的期望传输次数(ETX)为路由度量;而针对有移动节点参与的路由,采用新的RPL度量。每个移动节点依据信道条件产生置信区域,利用Kalman滤波修正移动节点位置。再依据经Kalman滤波后的修正位置和方差,移动节点重新构建置信区域,并形成候选锚节点集。最终,移动节点利用端到端ETX估计值,选择最优的路径。仿真结果表明,与传统的RPL协议相比,KPRPL协议提高了在恶劣环境下的可靠性和鲁棒性。     

一种高效低时延的RPL跨层优化机制

低功耗有损网络路由协议RPL中的路由度量存在一定局限性,从而导致网络拓扑不均衡以及数据传输路径非最优等问题.提出一种高效低时延的RPL跨层优化机制CL-ORPL.综合考虑网络深度、链路队列利用率以及期望传输次数等多种度量,以完善最优父节点选择机制.目的地通告对象确认消息(DAO-ACK)携带上一跳节点信息,通过跨层旁听...     

RPL的ETX路由度量研究

ETX(Expected Transmission Count)是现有的低功耗有损网络路由协议(Routing Protocol for Low power and Lossy Networks,RPL)采用的一种路由度量。ETX最小化了两个节点间成功传输一个数据包所需发送的次数,但在数据传输的实时性方面的考虑有所欠缺。在ETX的基础上最小化数据传输延时,保证数据传输的高成功率和低延时,最后在contikiOS中实现并与标准的ETX进行了比较。     

AdHoc路由协议性能分析

本文主要介绍了AdHoc网络三种典型路由协议,DSDV（Destination Sequenced Distance Vector）．TOR．A．（Temporally Ordered Routing Algorithm）,DSR（Dynamic Source Routing）。然后利用NS-2仿真软件对三种典型路由协议在包投递率,平均端到端时延方面进行了仿真和分析。最后总结了在不同节点移动速率下这几种路由协议的优缺点。     

多汇聚LLN中基于双向父节点选择的高效RPL路由协议

针对当前多汇聚LLN中RPL路由协议存在的雷鸣效应、待入网节点唯一决定父节点选择以及数据传输利用网络资源不够合理等问题,提出BPSM-ERPL——一种基于双向父节点选择的高效RPL改进路由协议。改进M-DAO消息使其携带数据传输速率信息,采用双向父节点选择新机制,防止大量待入网节点选择同一父节点,通过边界路由节点使数据在多个RPL实例中合理分配。理论分析和仿真实验结果表明,所提协议的网络吞吐量、数据分组传送成功率和网络生存时间优于现有相关协议。     

一种负载均衡的RPL多路径数据传输机制

低功耗有损网络路由协议(RPL)由于负载不均衡导致节点能耗失衡。为此,提出一种RPL多路径数据传输机制。在网络拓扑构建过程中依据数据传输代价选出每个节点的最优多父节点集。结合无线链路质量、节点剩余能量、节点缓存占用率以及中继节点的子节点数量等度量,设计一种数据流量分配度量标准,基于该度量标准提出能够最大化均衡网络负载的流量分配策略,以获得最优数据传输方案。仿真结果表明,相对RPL、ELT-RPL机制,该机制能够最大化地实现负载与节点能耗均衡,延长网络生存时间并提高路由可靠性。     

无线传感网络中RPL路由协议研究及性能分析

详细介绍了无线传感网络中的RPL(IPv6 Routing Protocol for Low-Power and Lossy Networks)路由协议,从仿真环境、参数设定、仿真场景设计等方面对RPL路由协议的仿真进行了分析。利用cooja模拟器对RPL路由协议进行了仿真,并针对分组递交率和平均功耗两个性能指标对RPL路由协议进行性能评估。仿真结果表明,RPL路由协议在分组递交率方面适用于各个场景,并能很好地适应网络的动态变化;在功耗方面不适用于树型空间位置的场景,并且对于动态变化的网络会大大增加平均功耗。     

一种基于博弈论的物联网路由策略研究

物联网的普及,对物联网的信息安全提出了更高的要求。低功耗有损网络（Routing Protocol for LLN,RPL）是主流的物联网通信协议,RPL根据中继节点的通信距离构建有向无环图（Destination Oriented Directed Acyclic Graph,DODAG）,以规划数据路由的路径。RPL协议无法应对主流的安全攻击,针对RPL设计一种低成本高可靠性的路由策略是目前物联网信息安全研究的一个主要方向。本文基于非合作博弈理论,设计了一种可以根据RPL协议中的节点上下文信息,发现并避让不良节点的路由策略。该方法的特点在于能够以较低的功耗开支提供与主流的加密策略相近的安全防护能力。仿真结果表明,所提方法在节点密度较高情况下性能良好。     

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.