基于程序段的可重构cache与处理器低能耗算法*

运用可重构cache和动态电压缩放技术,为处理器及其cache提出了一种基于程序段的自适应低能耗算法PBLEA（phasebased low energy algorithm）。该算法使用建立在指令工作集签名基础上的程序段监测状态机来判断程序段是否发生变化,并作出cache容量及CPU电压和频率的调整决定。在程序段内,使用容量调整状态机和通过计算频率缩放因子β来先后对cache容量及CPU电压和频率进行调整。在Simpanalyzer模拟器上完成了该算法的实现。通过对MiBench测试程序集的测试表明     

动态时间片缩放:一种优化Linux 任务公平性的方法

处理器动态电压频率调节技术,对Linux系统中并发任务的性能产生不同程度的变化,从而影响并发任务计算资源分配的公平性.提出了一种利用动态时间片缩放来优化任务公平性的方法,并基于Linux操作系统任务调度程序,加入动态时间片缩放模块,该模块通过读取CPU性能监控计数器,在线计算时间片缩放系数,并利用该系数对任务时间片长度进行动态缩放.实验表明,这种方法以较小的系统开销为价,极大地提高了Linux中并发任务计算资源分配的公平性.     

优化能耗的可变电压禁忌任务调度算法

能耗是影响异构式并行和分布式系统性能的一个重要因素,动态电压缩放(DVS)技术通过将处理器降低到不同频率来达到有效地节约能耗的目标。通常DVS技术包含任务调度及空闲时间片分配两阶段。当前绝大部分研究均针对时间片分配阶段,而在此考虑的是任务分配与空闲时间片间的关系。为了降低异构分布式系统的能耗,提出了一个利用禁忌(Tabu)策略进行调度的DVS算法。此算法首先调度用有向无环图(DAG)表示的任务集到处理器上,再应用禁忌策略来改进它,通过禁止任务再调度到特定处理器,从而增加时间片,分配阶段可用的空闲时间片达到进一步减少能耗的目标。仿真结果表明,本算法能有效地减少计算机系统的能耗。     

单处理器多外设实时系统全局能耗优化算法研究

在电池供电的实时嵌入式系统中,能耗是系统设计的一个重要研究问题.动态电压调度和动态电源管理是两种重要的节能技术.前者是动态改变处理器电压/频率,降低处理器能耗;而后者是动态调整片外设备的工作模式,减少片外设备能耗.目前只有少量研究把这两种技术综合在一起.本文研究支持这两种技术的嵌入式全系统实时任务节能调度问题.针对连续和离散处理器频率模型,论文分别提出高效的算法,通过计算系统运行的能耗最小处理器最优频率和设备最优空闲时间,来实现全系统综合节能的目的.实验模拟表明本文算法大大优于其他算法.     

基于程序访存行为的片上网络能耗优化方法

片上网络作为未来多核处理器片上互连的发展趋势,其能耗优化问题越来越受到重视。动态电压频率调节是一种有效的运行时能耗管理手段,近年来已被许多研究者用在片上网络的能耗优化上。针对目前主流的分布式控制方案存在软硬件代价高的缺点,提出了一种全局控制的能耗优化方法,通过监控程序的关键性访存信息来动态调整片上网络的电压和频率。仿真结果表明,在允许性能损失5%的限制下,该方法可以实现约45%的能耗节省。     

无线传感器节点低功耗的研究

为了最大限度地延长传感器节点的生存时间,电路、结构、算法和协议必须满足能量有效性.就单个传感器节点角度来看,可以节省能耗的方法有很多,其中动态功率管理(DPM)和动态电压调节(DVS)是两种有效节省CPU能耗的方法.在三星S3C2410芯片上测试,改变处理器的频率,验证了功耗和频率的线性关系.通过仿真分析了CPU能耗与缓冲器长度的关系,说明了缓冲器溢出概率对CPU功耗的影响关系,得出在DVS的基础上增加缓冲器长度或降低溢出概率可以进一步节省能耗.     

用于多核嵌入式环境的硬实时任务感功调度算法

充分考虑当前CMOS多核嵌入式处理器片上仅提供全局动态电压缩放(DVS)支持以及亚纳米时代后CMOS处理器泄露功耗不可忽视的现状,提出一种新的多核嵌入式环境中的硬实时任务感功调度算法GRR&CS。算法通过基于贪心法的静态任务划分,基于全局资源回收利用和任务迁移的动态负载均衡,以及动态核缩放三个步骤实现整体能耗的降低,并同时保证实时任务的可调度性约束。实验表明,提出的算法相比较现有算法多节省14.8%~41.2%的能耗。     

基于异构多核平台H．264解码的DVFS算法

异构多核作为嵌入式处理器架构的发展趋势,在处理复杂的视频编解码运算上具有强大的优势。但在实际应用中,多核所带来的能耗问题是其不得不面对的瓶颈。为克服这一问题,提出一种针对H．264的动态电压频率调节算法,通过对数据帧的解码工作负载进行预测,动态调整处理器的电压和频率,最终实现降低能耗的目的。实验结果证明,该算法至少可以降低处理器20％的能耗。     

基于周期性模式匹配的动态电压调节预测算法

zengyi2008@163.com 1 概述 随着计算机在嵌入式、微型化和便携应用等方面的发展,功耗成为重要指标。对于整个计算机系统来说,降低功耗的设计主要从逻辑层、物理层和系统层3个层面来进行。其中,在针对处理器的功耗调节算法中,动态电压调节(Dynamic Voltage Scaling, DVS)[1]被认为是目前最有效的算法。它根据 CPU的负载状况对处理器的供电电压和运行频率进行动态调节,在保证性能需求的前提下降低能量消耗。其算法主要分为2类：基于时间间隔的DVS算法,基于任务的DVS算法。 近些年来,为支持DVS算法降低处理器的运行能耗,不同硬件制造厂商在逻辑电路设计方面相继公布了各种技术,如Intel的speedstep技术,AMD的PowerNow及Cool’n’Quiet技术。然而,实际应用中的动态电压调节算法或多或少会影响系统的性能,主要原因是DVS算法对下一时间片的任务量预测不够准确,难以适应系统需求。 本文在对现有DVS算法分析的基础上,针对past算法预测准确率低的现象进行了改进,在past预测方法中加入周期性模式匹配(Cycle Mode Matching, CMM)预测方式。并对改进算法进行了仿真对比,结果表明改进算法在用户干预少的情况下能有效提高预测的准确性。 2 相关工作 文献[1]给出了3种经典的电压调节算法：opt, past, future。opt和future算法假设可以看到将来一段时间内的CPU使用情况,降低工作频率将运行时间延伸以填补所有的空闲时间周期,从而减少能耗;past算法则将future算法向前看一个时间片改为往后看一个时间片,并假设前后2个时间片内处理器的工作量不变,从而预测出下一时间片处理器的工作量,调节频率以适应当前工作量,达到能耗的节省。     

开销敏感的多处理器最优节能实时调度算法

嵌入式多处理器系统的能耗问题变得日益重要,如何减少能耗同时满足实时约束成为多处理器系统节能实时调度中的一个重要问题.目前绝大多数研究基于关键速度降低处理器的频率以减少动态能耗,采用关闭处理器的方法减少静态能耗.虽然这种方法可以实现节能,但是不能保证最小化能耗.而现有最优的节能实时调度未考虑处理器状态切换的时间和能量开销,因此在切换开销不可忽视的实际平台中不再是最优的.文中针对具有独立动态电压频率调节和动态功耗管理功能的多处理器系统,考虑处理器切换开销,提出一种基于帧任务模型的最优节能实时调度算法.该算法根据关键速度来判断系统负载情况,确定具有最低能耗值的活跃处理器个数,然后根据状态切换开销来确定最优调度序列.该算法允许实时任务在处理器之间任意迁移,计算复杂度小,易于实现.数学分析证明了该算法的最优性.     

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.