基于Linux内核的进程检查点系统设计与实现

作为一种流行的软件容错机制,检查点与恢复技术的实现模式有两种:用户级和系统级.首先阐述了两者的区别,然后根据Linux可加栽内核模块机制提出了一种基于Linux内核的进程检查点与恢复实现方法.利用Linux内核线程实现了检查点与恢复内核模块,并基于此内核模块在用户层构造了一检查点函数库,为用户提供了相应接口.用户通过组合使用这些接口可以高效地实现具体检查点与恢复算法.     

二阶可逆耦合触发细胞自动机的加密技术研究

为了有效改进细胞自动机加密系统的实现复杂度和加解密效率,提出了一种二阶可逆耦合触发细胞自动机的图像加密方法.通过对简单的可逆细胞自动机进行扩展,构造二阶可逆细胞自动机,并以耦合触发规则对明文图像实行分块加密.二阶可逆细胞自动机的转移状态由其当前状态以及前一状态决定,有效增大了邻域范围,并且因为采用耦合触发规则,因此能明显增大加密系统的密钥空间,保证了系统的计算安全性.与一般触发自动机反向迭代的串行加密方式相比,该方法对于每个细胞的加密具有本质并行性,因此具有极高的加解密效率.通过实验验证其性能,结果表明与其它算法相比,该算法具有较大的密钥空间,能够有效抵抗蛮力攻击和差分分析攻击,且较小的邻域半径即可得到良好的加密效果,因此非常便于硬件实现.     

支持构件迁移的分布式系统容错算法

随着分布式应用技术的发展,构件的静态性限制了分布式系统在运行期间适应其可用资源变化的要求.为了动态适应系统可用资源,提高系统性能,支持构件可迁移的分布式应用研究受到广泛关注.针对提高构件可迁移分布式应用的可靠性,提出一种分布式系统容错算法.在准同步检查点算法的基础上,通过引入shadow-chain和通讯录机制,实现了构件间通信的可靠性和构件重定位的透明性,从而使得系统能够在较低代价下设置检查点,并能将出错后的系统回卷到一致性状态.     

基于深度强化学习的雾计算容器整合

在雾计算系统架构基础上, 针对数据中心高能耗、应用任务负载的随机动态性以及用户对应用的低时延要求, 提出一种基于A2C (advantage actor-critic)算法的以最小化能源消耗和平均响应时间为目标的容器整合方法, 利用检查点/恢复技术实时迁移容器, 实现资源整合. 构建从数据中心系统状态到容器整合的端到端决策模型, 提出自适应多目标奖励函数, 利用基于梯度的反向传播算法加快决策模型的收敛速度. 基于真实任务负载数据集的仿真实验结果表明, 该方法能够在保证服务质量的同时有效降低能耗.     

改进的快速N＋1奇偶校验检查点

本文运用缓冲区和增量有盘检查点相结合的技术提出了一个快速可靠的改进N+1奇偶校验检查点方案。在N个应用进程运行时，通过设置一个专用的检查点进程来实现N+1的奇偶校验，并且利用检查点机在检查点间隔的空闲时间将增量的奇偶校验检查点信息保存到稳定的存储器中。改进的算法利用了无盘检查点方案的快速及磁盘检查点的高可靠性，减少了一台备份处理机，并且可容忍一个应用进程及一个检查点进程的两个并发错误。     

基于虚拟文件操作的文件检查点设置

实现分布/并行系统容错的基础是单进程检查点设置和卷回恢复技术,而对活动文件信息进行保存和恢复则是这种技术的重要方面.提出一种虚拟文件操作策略,实现了对用户文件的检查点设置,有效地解决了发生故障时用户文件内容与进程全局状态的不一致的问题.该方法通过文件块式管理、检查点分布操作等技术,使得在空间开销、正常运行时间、恢复时间等性能指标上优于其他方法,并且具有对用户透明、可最大限度地保留已完成工作的特点.     

GECISM中的回滚、备份与设障

检查点技术用来对系统中正常运行的程序有效状态进行备份，当系统出现故障时，可以根据最近的检查点恢复当前失效的进程，减少计算的损失。由不同的代理构成的计算机免疫系统GECISM(GEneral Computer Immune System Model)是把生物免疫系统的机理用于计算机安全领域的一个产物。通过比较多种不同的检查点机制，选择利用缓冲回滚系统BRAS(Buffering RollbAck System)检查点机制实现GECISM中类TD代理功能，使系统回卷到以前洁净点状态。     

一种改进的同步检查点设置算法

检查点设置与卷回恢复是集群系统中容错计算的重要手段.同步检查点方法在集群系统中得到了广泛应用.为了提高集群计算系统的工作效率,降低系统的容错开销,根据基于消息驱赶的同步检查点设置算法的性质和在实际应用中并行应用程序的通信特征,通过减小协同过程中的阻塞时间,降低系统中控制消息的数量,对基于消息驱赶的Syncand-Stop算法进行优化.改进的算法有效降低检查点设置的时间和空间开销,减小在系统应用中检查点设置的代价,进一步提高系统可扩展性和应用可靠性.     

MPP机检查点系统的设计与实现

检查点技术是一种回溯和恢复的技术，在并行应用环境中，作用尤为突出。它定期保存程序的运行状态，以便需要时能及时从中恢复。本文系统介绍了检查点技术的基本概念和实现细节，详细阐述了ＭＰＰ机检查点系统的设计思想，探讨了其中的主要问题－检查点的状态一致性以及检查点的性能优化措施。本文的结论是：我们能够在ＭＰ系统中实现高效的检查点技术，以此来提高此类系统的可用性。     

一种分布容错系统中的检查点设置技术

本文提出一种在分布处理环境中,消除向后恢复过程中多米诺效应的检查点设置技术,其优点是功能强,代价小、适用面广而且实现简单.在理论分析的基础上,本文提供了该技术的实现方案,检查点存储管理方法及其评价技术.     

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.