MapReduce中Combine优化机制的利用

由Apache软件基金会开发的Hadoop分布式系统基础架构,作为一个主流的云计算平台,其核心框架之一的MapReduce性能已经成为一个研究热点,其中对于Shuffle阶段的优化,使用Combine优化机制是关键.文章详细介绍了MapReduce计算框架及Shuffle流程;分别从机理简介、执行时机、运行条件三方面详细阐述了如何利用Combine优化机制;通过搭建Hadoop集群,运用MapReduce分布式算法测试实验数据.实验结果充分证明,正确地运用Combine优化机制能显著提高MapReduce框架的性能.     

云计算环境下朴素贝叶斯文本分类算法的实现

采用分布式编程MapReduce模型研究了文本统一格式预处理、训练、测试以及分类等基于朴素贝叶斯文本分类算法主要计算过程的MapReduce并行化方法,并在Hadoop云计算平台进行了实验。实验结果表明：朴素贝叶斯文本分类算法MapReduce并行化后在Hadoop云计算平台上部署运行,具有较好的加速比,对中文网页文本分类识别率达到了86%。     

适于进化算法的迭代式MapReduce框架

MapReduce模块化的编程大大降低了分布式算法的实现难度,但同时也限制了它的应用范围。介绍了MapReduce的基本结构及其实现迭代算法的缺陷,并针对基于MapReduce进化算法效率低下的问题,在对MapReduce的计算框架进行研究的基础上提出了一种适用于进化算法的迭代式MapReduce计算框架。描述了迭代式MapReduce计算框架的实现需求及其具体实现,提出并证明了异常机制的可行性,且在公有的Hadoop云计算平台上对提出的框架进行了验证。实验结果表明,基于迭代式MapReduce计算框架的并行遗传算法在算法的加速比上与基于MapReduce的并行遗传算法相比有较大的提高。     

大数据处理平台比较与分析

虽然以MapReduce和Hadoop分布式系统(HDFS)为核心的Hadoop已在大规模数据密集的商业领域成功应用,但是对于多个并行操作之间重用工作数据集却表现不佳。作为对其的一种补充,本文介绍了Spark。首先介绍Hadoop的MapReduce与HDFS基本概念与设计思想,然后介绍了Spark的基本概念与思想,并且着重介绍了弹性分布式数据集RDD,并通过实验证明和分析对比了Hadoop与Spark。     

基于Hadoop框架的MapReduce计算模式的优化设计

对某高校教学资源平台的海量日志进行了分析,将传统单机分析处理模式,转变为Hadoop框架下的MapReduce分布式处理模式。MapReduce采用分而治之的思想,很好地解决了单机对海量数据处理产生的瓶颈问题。通过分析Hadoop源码的使用,认真研究MapReduce对海量数据处理作业流程分析,提出了MapReduce分布式作业计算的优化策略,从而更好地提高了海量数据的处理效率。     

Hadoop云平台MapReduce模型优化研究

针对Hadoop平台MapReduce分布式计算模型运行机制中的顺序制约而产生的计算资源浪费问题,从提高平台中每个执行节点的细粒度并行数据处理角度出发,结合Java共享内存多线程编程技术,对该模型进行了优化,提出一种MapReduce+OpenMP粗细粒度相结合的分布式并行计算模型。并在由四个节点组成的Hadoop集群环境下对不同规模大小的出租车GPS轨迹数据分析处理,验证该模型的性能和效率,实验结果证明MapReduce+OpenMP分布式并行计算模型确实能够提高针对大数据集的计算效率,是对Hadoop平台大数据分析处理模型有效的完善和优化。     

基于Hadoop的广域网分布式主题爬虫系统框架

广域网分布式爬虫与局域网爬虫相比有诸多的优势,而现有基于Hadoop分布式爬虫的设计主要是面向局域网环境的。为解决Hadoop分布式计算平台不适合部署于广域网的问题,设计了一个基于Hadoop的广域网分布式爬虫系统框架。爬虫系统利用消息中间件实现分布式可靠通信,数据存储采用可伸缩的Hadoop分布式文件系统HDFS,网页解析利用MapReduce并行处理,并基于模板匹配实现框架可定制。系统的性能仿真显示该框架具有支撑大规模爬虫并发工作的能力。     

Hadoop云计算平台在视频转码上的应用

视频转码是一种计算密集型和数据密集型的工作，需要消耗大量的计算机资源，Hadoop MapReduce是一种软件模型，支持大规模数据集的分布式处理．．利用已有开源视频转码软件ffmpeg建立一个基于MapReduce框架的Hadoop集群转码系统，提高视频转码的速度．     

基于Hadoop平台的数据挖掘技术研究

Hadoop集MapReduce、HDFS、HBase、Avro、Pig等子项目于一身,并行编程模型(MapReduce)、分布式文件系统(HDFS)是Hadoop的核心技术。用户可以通过结合编程模型MapReduce与Hadoop的方式对分布式程序进行进行二次开发,从海量数据中挖掘隐含的、新颖的、对决策实施工作有指导价值的关系、模型,在Hadoop平台上构建数据挖掘系统。     

基于MapReduce的分布式光线跟踪的设计与实现

提出了基于MapReduce架构实现分布式光线跟踪渲染的方案。该方案基于Hadoop实现，利用MapReduce架构简化了分布式程序设计。使用分布式计算进行光线跟踪，充分利用了现有低端硬件设备的处理能力。实验表明，该方案通过并行计算大大加快了渲染速度。     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。