面向数据收集的转发树构建与链路调度算法

多数基于压缩感知的数据收集方法假设网络无干扰或能够采取有效的冲突避免措施,当网络存在干扰或噪声时,难以同时兼顾效率和可靠性。为此,以压缩感知理论为基础,研究物理干扰模型下的数据收集问题,将其建模为转发树构建和链路调度联合问题,并设计可构建转发树的分布式求解算法,确定一组转发树并在调度后于最短调度周期内将测量数据发往汇点,实现传输延时和采集能效间的平衡。仿真结果表明,该算法能有效降低数据传输延时,提高数据采集能效。     

基于反向平衡聚合树的无线传感器网络分布式TDMA调度算法*

讨论了已有的TDMA算法在端到端延时上的弊端,在优化时隙数的基础上引入链路的使用顺序与数据流向的相关性,提出了分布式TDMA调度算法,利用反向平衡聚合树的生成过程分配时隙,通过控制链路染色顺序分布式优化延时与避免冲突。仿真结果验证了算法在端到端延迟和通信开销上的性能提升。     

无线传感器网络中的改进数据聚集调度算法

针对现有聚集数据调度近似算法具有较高延时上界的问题,提出一种改进的聚集数据调度近似算法。建立一棵根在中心结点的广度优先搜索树,分层构造一个最大独立集(MIS),使MIS中相邻的2个结点相距两跳。将MIS中的结点连接起来,形成一棵根在中心结点的数据聚集调度树,使结点按数据聚集调度树进行分层数据调度。在数据聚集调度树的构造过程中,对于任意支配点,以最小的结点连接其相距两跳的支配点。对于2个相邻支配点的公共邻居支配点,通过在距中心点最近的支配点加入数据聚集树,使其在数据调度过程中将数据发送给距中心点最近的支配点,从而降低数据的聚集延时。实验结果表明,与SAS算法、Guo’s算法和IAS算法相比,该算法的数据聚集延时更低,其延时上界为14R+△?10。     

无线传感网中一种改进的分布式数据聚集调度算法

针对无线传感器网络中实时数据收集具有较高的延时问题, 提出了一种改进的无通信冲突的分布式数据聚集调度近似算法。该算法首先在最大独立集的基础上建立一棵根在sink的数据聚集树, 然后各个节点按数据聚集树分层进行数据调度。在数据聚集树的构造过程中, 对于两个相距两跳的支配点, 它们共同的、相距两跳的支配点, 通过距sink最近的支配点加入数据聚集树; 而在数据调度过程中, 采用一种新的选择标准从竞争集中选择节点进行数据调度。通过这两方面的改进, 有效地降低了数据的聚集延时。理论分析表明, 该算法的延时上界为14R+Δ; 仿真模拟的结果表明, 该算法产生的数据聚集延时远低于现有算法。     

基于物理干扰模型的无通信冲突的数据聚集调度算法

针对基于物理干扰模型的最小延时数据聚集调度问题,提出一种改进的无通信冲突的数据聚集调度算法.该算法采用簇与局部聚集树相结合的调度机制,首先在小区域范围内形成簇,当头节点聚集簇内成员节点的数据后,这些头节点再在一个较大的区域内形成新的簇.与现有算法相比,该算法不是将簇内各成员节点的数据直接传输给头节点,而是先构造一棵根在头节点的局部数据聚集树,然后将整个网络划分为若干个边长相等且只包含一个节点的正方形区域,最后对节点所在区域进行着色,使颜色相同、其孩子节点为空或已完成数据调度的簇内成员节点根据局部聚集树进行数据调度.实验结果表明,与现有算法相比,该算法的数据聚集延时更低,其延时上界为(5 +logK+1△) (K+ 1)2.     

受SINR约束的最小延时数据聚集调度算法

针对现有的基于物理干扰模型的数据聚集调度近似算法具有延时较高的问题,提出了一种改进的数据聚集调度近似算法。该算法首先构造一个连通支配集作为数据聚集树,使各节点根据数据聚集树分层进行数据调度;然后将整个网络划分为若干个边长相等的正方形区域,使每个区域中最多包含一个支配节点;最后对各个区域进行着色,并从颜色相同的每个正方形区域中任选一个普通节点,使它们能同时将数据汇聚到相应的支配节点。当数据从所有普通节点聚集到相应支配节点后,则将这些正方形区域构成一个大小相同的块,并采用四种颜色对这些块进行着色,使颜色相同的各个块中任选一条通信链路能够同时进行数据传输而不会发生通信冲突和干扰。理论分析表明,该算法的延时上界为K2Δ＋8K2R-3R;仿真模拟的结果表明,该算法产生的数据聚集延时低于现有算法。     

WSN中基于最小延时的数据汇集树构建与传输调度算法

针对现有的无线传感器网络数据汇集算法延时较大的不足,对最小延时数据汇集树和传输调度问题进行了研究。提出一种基于度约束的汇集树构建算法(DCAT)。该算法按照BFS方式遍历图,当遍历到每个节点时,通过确定哪些节点与汇点更近来确定潜在母节点集合。然后,选择图中度数最小的潜在母节点作为当前被遍历节点的母节点。此外,为了在给定的汇集树上进行高效的数据汇集,还提出两种新的基于贪婪的TDMA传输调度算法:WIRES-G和DCAT-Greedy。利用随机生成的不同规模的传感器网络,参照当前最新算法,对所提方法的性能进行了全面评估。结果表明,与当前最优算法相比,将所提调度算法与所提汇集树构建算法结合起来,可显著降低数据汇集的延时。     

一种传输能量固定的数据聚集调度近似算法

针对现有的基于物理干扰模型的数据聚集调度近似算法具有较高的延时问题, 提出了一种改进的传输能量固定的数据聚集调度近似算法。该算法首先根据节点的通信半径构造一个网络通信图, 然后在该通信图中构造一棵数据聚集树, 使节点根据数据聚集树分层进行数据调度。在数据调度过程中, 首先将整个网络划分为若干个圆形区域, 然后对各个区域进行着色, 最后对颜色相同的区域同时进行节点的数据调度。理论分析表明, 该算法的延时上界为（X+1）²(Δ+12R+4)+R。仿真模拟结果表明, 该算法产生的数据聚集延时远低于现有算法。     

无线传感器网络中基于最小延时的数据汇集树构建与传输调度算法

无线传感器网络的数据通信模式问题是目前的研究热点,针对现有的无线传感器网络数据汇集算法延时较大这一不足,对最小延时数据汇集树和传输调度问题进行了研究。提出一种基于度约束的汇集树构建算法(DCAT)。该算法按照 BFS 方式遍历图,当遍历到每个节点时,通过确定哪些节点与汇点更近来确定潜在母节点集合。然后,选择图中度数最小的潜在母节点作为当前被遍历节点的母节点。此外,为了在给定的汇集树上进行高效地数据汇集,还提出两种新的基于贪婪的TDMA传输调度算法：WIRES-G 和 DCAT-Greedy。利用随机生成的不同规模的传感器网络,参照当前最新算法,对文中方法的性能进行了全面评估。结果表明,与当前最优算法相比,文中调度算法与文中汇集树构建算法结合起来,可显著降低数据汇集的延时。     

5G超密集异构网络带内无线回传资源分配方案

为实现5G超密集异构网络中无线回传链路和接入链路之间的最优资源分配,研究多用户场景下双层异构网络的联合用户调度和功率分配问题,在队列稳定和无线回传资源有限的情况下,综合考虑用户调度、功率分配和干扰控制等因素,对带内无线回传的最优资源分配问题进行数学建模并求解,基于李雅普诺夫优化理论提出联合用户调度和功率分配的优化算法。将优化问题解耦为网络内各个用户的调度以及宏基站和小基站的功率分配过程,采用MOSEK求解器和二分类方法获得用户调度向量,利用拉格朗日乘子法求解功率分配问题,并通过队列的时刻更新过程实现最优资源分配。仿真结果表明,在多用户场景下,该方案能够有效提升网络总吞吐量以及网络效用,并且毫米波频段的通信性能优于传统蜂窝网络频段。     

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.