一种高可用对象存储系统的数据组织研究

通过对现有不同存储系统的容错能力进行认真分析,提出了一种新的高可用对象存储系统架构HAOSS(High Availability Object Storage System).HAOSS系统分两层:上层存储的对象采用在多个设备之间的数据备份的方式来实现高可靠性,多个备份能够同时对外提供服务,保证系统的高性能,但是磁盘利用率比较低.下层采用RAID5,RAID6以及RAID_Blaurn等不同的容错编码来实现多盘容错功能,磁盘利用率较高,但是由于编码越来越复杂,容错编码需要大量的计算,性能受到很大的影响.在数据组织上,新对象和热点对象放上层,这样大部分请求都能够在上层命中,从而保证系统的性能.下层主要用来放不常用的数据.磁盘利用率比较高.在1000Mbps以太网环境下对HAOSS性能进行了测试,结果表明,HAOSS顺序读写性能都比较好,最大可以达到104MB/s,达到1000Mb以太网的理论最大物理带宽.     

面向混联机床的机械系统容错重构规划方法研究

提出了一种机械系统可重构的混联机床,研究了混联机床机械系统的容错重构策略,提出了基于机构类型演化的机械系统重构容错新方法,给出了球铰演化为虎克铰的实施方案.导出了故障和非故障状态下混联机床的位置反解算法,在ADAMS平台中进行了仿真分析和研究,得到了容错重构前后自旋角的变化曲线以及各驱动腿的长度和工作台位移的变化曲线.仿真结果表明,利用混联机床的机械系统可重构性能可以提高混联机床的可靠性和安全性.     

VLSI冗余单元最优分配的遗传算法求解

随着VLSI芯片面积的增加和电路复杂性的增强,芯片的成品率受制造缺陷影响的概率逐渐增加。为了解决这一问题,人们将容错技术结合入集成电路设计中。要使一个系统具有较强的容错能力,必须给系统提供一定量冗余单元。本文利用遗传算法有效地解决了使系统成品率达到最大的冗余单元最优分配问题。     

近阈值电压下可容错的末级缓存结构设计

近阈值电压技术通过降低晶体管的电源电压来降低芯片能耗和提升能效。但是,近阈值电压技术会在Cache中引起大量位错误,严重影响末级缓存的功能。针对近阈值电压下超过1%的位错误率造成的Cache故障问题,该文提出一种基于传统6T SRAM单元的可容错的末级缓存结构(FTLLC)。该策略对缓存条目中的错误进行了低错纠正和多错压缩,提高了Cache中数据保存的可靠性。为了验证FTLLC的有效性,该文在gem5中实现了该结构,并运行了SPEC CPU2006测试集进行仿真实验。结果表明,对于650 mV电压下65 nm工艺的末级缓存,FTLLC与Concertina压缩机制相比在4-Byte粒度下末级缓存可用容量增加了24.9%,性能提高了7.2%,末级缓存的访存缺失率下降了58.2%,而面积和能耗开销仅有少量增加。     

Decentralized fault-tolerant control system design for unstable processes

Fault-tolerant control is an important issue in control of mission critical processes. In this paper, a new approach to fault-tolerant control of unstable processes is proposed based on the Passivity Theorem. The control system is designed in two sequential steps: A multi-loop proportional controller is used to stabilize the unstable process; a passivity-based decentralized unconditionally stabilizing (DUS) controller is then applied to the stabilized process. While the multi-loop stabilizing controllers need to be built with redundancy, the DUS controller is inherently fault tolerant and can maintain closed-loop stability when any of its loops fail. By using a stabilizing proportional controller with the fewest loops, control redundancy can be reduced to the minimum level.     

Edge-fault-tolerant diameter and bipanconnectivity of hypercubes

Let n(?3) be a given integer and . And let Qn be an n-dimensional hypercube and F⊂E(Qn), such that every vertex of the graph Qn−F is incident with at least two edges. Assume x and y are any two vertices with Hamming distance H(x,y)=h. In this paper, we obtain the following results: (1) If h?2 and |F|?min{n+h−1,2n−5}, then in Qn−F there exists an xy-path of each length l∈Ωh+2, and the upper bound n+h−1 on |F| is sharp when 2?h?n−4, and the upper bound 2n−5 on |F| is sharp when n−4?h?n−1 and h=2. (2) If |F|?2n−5, then in Qn−F there exists an xy-path of each length l∈Ωs, where s=h if n−1?h?n, and s=h+2 if n−4?h?n−2 and h?2, and s=h+4 otherwise. Hence, the diameter of the graph Qn−F is n. Our results improve some previous results.     

Bibliographical review on reconfigurable fault-tolerant control systems

In this paper, a bibliographical review on reconfigurable (active) fault-tolerant control systems (FTCS) is presented. The existing approaches to fault detection and diagnosis (FDD) and fault-tolerant control (FTC) in a general framework of active fault-tolerant control systems (AFTCS) are considered and classified according to different criteria such as design methodologies and applications. A comparison of different approaches is briefly carried out. Focuses in the field on the current research are also addressed with emphasis on the practical application of the techniques. In total, 376 references in the open literature, dating back to 1971, are compiled to provide an overall picture of historical, current, and future developments in this area.     

在分区故障情况下分布式数据库的一个容错策略

本文提出了一种在分区故障情况下管理分布式数据库系统的方法——综合法,它不仅提高了可用性而且保证了数据的正确性或可恢复性.本文还介绍了模拟系统SDDB,分析了模拟三种网络分区后的处理算法:主复本法、quorum法,综合法的执行情况.