持续数据保护在发电企业的应用研究

随着发电企业系统数据量的不断增加,传统的数据保护方式已经不能完全满足业务发展的需要,亟需搭建一个具有更高可用性的数据保护系统,持续数据保护(CDP)技术正好可以满足这一要求。本文主要介绍了持续数据保护(CDP)的概念和特点,并探讨了它在发电企业中的应用,以供参考。     

基于虚拟存储技术的持续数据保护机制

为了解决信息系统中数据失效的问题,详细记录数据的变化情况,在灾难发生时能够最低限度的减小损失,分析了当前持续数据保护(CDP)技术的现状,立足现有的TRAP-4持续数据保护思想,提出了一种基于虚拟存储技术的持续数据保护机制(VPS_ CDP).在虚拟层改进了日志生成方式,减轻了系统工作负载,缩短了数据备份与恢复时间,并提出了基于文件块的持续保护思想,增强了系统对于核心数据的持续全备份能力.     

持续数据保护技术的优势分析

随着数据在如今信息社会中的作用越来越重要,数据的保护变得必不可少。新兴的数据保护技术持续数据保护技术CDP(Continuous Data Protection)一出世就成为关注的焦点,它用低成本和低复杂性提供很好的恢复点对象RPO(Recovery Point Ob-jective)和恢复时间对象RTO(Recovery Time Objective),增强了数据保护能力,实现了数据的快速恢复,增强了业务的连续性,成为对传统数据保护技术的重大突破。对CDP技术进行介绍,分析出传统数据保护技术如备份、复制和快照技术的劣势,总结出CDP技术与传统数据保护技术相比具有的优势以及CDP是如何解决传统数据保护技术的缺陷。     

远程镜像系统容错机制的研究与实现

针对基于FreeBSD的远程镜像系统FRM在运行时存在5种可知错误(发生灾难、磁盘I/O错误、运行环境错误、系统错误、网络错误)设计容错策略,通过状态机实施错误恢复。实验结果证明,该容错机制可以确保在错误发生时最大限度地保证数据的完整性和一致性,使FRM从各种错误中恢复,继续进行数据保护的任务。     

SnapCDP:一种基于LVM的CDP机制的设计与实现

连续数据保护(continuous data protection,CDP)是一种数据的连续时间点的保护技术,它能在故障瞬间完成任何时间点的故障恢复,起到业务的快速连续地运行的作用.与传统的数据保护技术相比,CDP可以提供更灵活的目标恢复点和更快的目标恢复时间.实现了一种名为SnapCDP的基于LVM(logical volume management)的CDP机制.SnapCDP是将CDP模块嵌入到LVM中来实现的.实验表明,SnapCDP可以利用较短的时间将数据恢复到用户设定的历史时间点.     

高性能块级CDP系统的研究与设计

为解决现有块级持续数据保护技术对系统写性能影响过大的问题,通过对CDP读写过程进行研究分析,设计了一种Linux下基于设备映射机制的块级CDP系统设计方案.该方案使用缓存队列和后台数据同步技术,减少写操作时的磁盘IO操作次数,并通过读状态映射表实现数据的正确读取.测试结果表明,该方案在较少损失系统读性能的条件下,可获得较高的写性能.     

海量数据持续数据保护技术研究及实现

持续数据保护(continuous data protection,CDP)是一种在不影响主要业务系统运行的前提下,可以实现持续捕捉或跟踪目标系统所发生的任何改变,并且能够恢复到此前任意时间点的方法.提出了一种新的可扩展的海量数据持续数据保护技术;设计基于块级的海量数据持续数据保护技术的体系架构、关键技术.最后对系统性能进行了对比分析,并进行了总结和展望.     

连续数据保护中的滑动窗口技术的优化

连续数据保护技术是减少企业数据损毁的重要方法。由于每次需要对I/O进行备份,存储空间的容量成为限制CDP有效备份时间长度的主要因素。然而,对于大多数应用来说,其出现峰值写入的情况并不常见,存储资源浪费严重。本文以传统滑动窗口机制为基础,将其进行优化,实现基于I/O负载变化的窗口自动调整,有效地提高存储资源的利用率,使用户可以利用有限资源,在绝大多数情况下拥有更好的数据保护能力。实验表明该方案不仅提高了备份盘的利用率,而且减少了数据恢复的最大数据丢失量(Recovery Point Object,RPO)。     

数据保护新热点

CDP(持续数据保护)捕获和保护数据中所有的变化,而非仅仅是某个预先选定的时间点。这样就可以随时访问数据,减少数据损失并消除代价高昂的停机损失。     

一种改进的块级连续数据保护机制

随着存储技术的快速发展,连续数据保护 (CDP) 功能已成为现代存储系统重要的数据保护和恢复手段.根据当前不同CDP实现机制的优缺点,提出了一种基于TRAP-4的改进机制--ST-CDP.在保留TRAP-4原有数据记录方式的基础上,按一定间隔值d在恢复链条中插入对应时间点的快照数据,有效地解决了TRAP-4的链条易失效和恢复时间过长问题.借助量化分析模型分析了该机制的性能并确定最优的d值.原型系统在Linux内核块设备层的RAID5上实现了该机制,并通过实验对3种不同CDP机制进行对比测试.实验结果表明ST-CDP既具有与TRAP-4类似比快照机制存储开销低、系统性能影响小的优点,还具有比TRAP-4更快的恢复效率及更高的可靠性.因此ST-CDP是一种高效并且恢复成本较低的连续数据保护机制.     

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.