Design and implementation of a fault tolerant controller for EMS systems

Conventional EMS (electromagnetic suspension) systems are susceptible to instability problems, and could even break down upon failures of the air-gap sensor or the accelerometer. Therefore, in order to improve EMS performance, a fault tolerant controller and a fault detection and isolation (FDI) algorithm are presented in this work. The fault tolerant controller is an extended version of the linear fault tolerant controller designed for known actuator or sensor failures, and it adopts the LMI-based H_∞ control for a class of nonlinear systems. The fault detection algorithm employs fuzzy inference. The merits of the proposed control scheme have been verified by the experiments with a single-axis two-magnet suspension system subjected to failures of the actuator or the sensors.     

基于遗传算法的异构系统多副本容错调度算法

针对异构系统中基于多副本机制的容错调度方法忽略调度makespan、任务间依赖与系统链路失效及严格调度方式调度makespan较长问题,首先提出通用调度方式下同时考虑节点和链路失效的可靠性计算方法;然后给出该通用调度问题的0-1整数规划模型;接着提出可靠性意识多副本任务通用调度(RAMD_TGS, reliability-aware multi-duplication task general scheduling)算法,通过遗传算法种群进化来搜索副本映射节点和开始执行时间。实验表明该算法不仅满足可靠性要求,而且与严格调度方式相比能进一步减小调度makespan,该算法资源占用开销也是可接受的。     

A distributed algorithm for energy efficient and fault tolerant routing in wireless sensor networks

Wireless Networks - Energy conservation and fault tolerance are the most two important challenging issues for the development of large scale wireless sensor networks (WSNs). Failure of cluster...     

A novel fault tolerant token ring network

Token Ring Networks have gained popularity due to their simplicity and ease of maintenance. However, the functioning of the entire network is dependent on the well being of an entity called “token”. The network ceases to function if the token is lost. There are algorithms suggested for improving the fault tolerant capabilities of the network with respect to the token.This paper proposes an algorithm to achieve fault tolerance. The algorithm is implemented on a simulated token ring network.     

A fault tolerant routing scheme for hypercubes

An efficient distributed fault‐tolerant routing algorithm for the hypercube is proposed based on the existence of a complete set of node‐disjoint paths between any two nodes. Node failure and repairs may occur dynamically provided that the total number of faulty nodes at any time is less than the node‐connectivity n of the n‐cube. Each node maintains for each possible destination which of the associated node‐disjoint paths to use. When a message is blocked by a node failure, the source node is warned and requested to switch to a different node‐disjoint path. The methods used to identify the paths, to propagate node failure information to source nodes, and to switch from one routing path to another incur little communication and computation overhead. We show that if the faults occur reasonably apart in time, then all messages will be routed on optimal or near optimal paths. In the unlikely case where many faults occur in a short period, the algorithm still delivers all messages but via possibly longer paths. An extension of the obtained algorithm to handle link failures in addition to node failures is discussed. We also show how to adapt the algorithm to n‐ary n‐cube networks. The algorithm can be similarly adapted to any interconnection network for which there exists a simple characterization of node‐disjoint paths between its nodes. This revised version was published online in June 2006 with corrections to the Cover Date.     

A cluster based WSN fault tolerant protocol

A Wireless Sensor Network(WSNs) fault-tolerant protocol is proposed in this paper.By setting up a robust cluster topology,the fault-tolerant algorithm can search any faulty node in the path and revise the path furthermore.Once the cluster head fails,it will be substituted by other alternative cluster heads with the lowest cost,and the path will be re-established.Experiments show that this algorithm can not only locate the faulty nodes in the path accurately,shield the influence of the error node in clusters...     

基于Goertzel算法的红外气体检测方法

基于红外热释电原理的测量方法有测量方便、寿命长、功耗低等优点,因此,红外热释电测量气体在城市管网、环境监测等场合的气体测量监控系统中得到了广泛应用。在红外热释电气体测量过程中,测量结果易受多频段信号的干扰,直接导致测量精度不高。因此,提出基于Goertzel算法的红外热释电气体测量方法,对AD获取的信号进行数字滤波处理。仿真分析并对比Goertzel算法和移动平均算法的滤波效果,仿真结果表明:Goertzel算法滤波误差为0.166 7%,测量波动为0.058%,比移动平均算法精度和稳定度分别提高51倍和18.4倍。最后通过搭建实验系统进行测试,结果表明:Goertzel滤波算法能有效地提高整体气体浓度测量精度和稳定度,测量精度能达到4 ppm左右。     

On fault tolerant matrix decomposition

We present a fault tolerant algorithm for matrix factorization in the presence of multiple hardware faults which can be used for solving the linear systemAx=b without determining the correctZU decomposition ofA. HereZ is eitherL for ordinary Gaussian decomposition with partial pivoting,X for pairwise or neighbor pivoting (motivated by the Gentleman-Kung systolic array structure), orQ for the usualQR decomposition. Our algorithm generalizes that of Luk and Park whose method allows for the correction of a single error in a single iterate of the matrixU. Using ideas from the theory of error correcting codes we prove that the algorithm of Luk and Park can in fact tolerate multiple errors in multiple iterates ofU provided these are all confined to a single column. We then generalize the algorithm to one that tolerates multiple errors in multiple iterates ofU provided they are confined to two columns. Our procedure for identifying the erroneous columns is based on the extended Euclidean algorithm and it analogous to the decoding algorithms for BCH codes. We indicate how our methods may be adapted to apply to any number of columns and finally we show how to compute a correct factorization ofA.The author gratefully acknowledeges financial support from the International Fund for Ireland. ¢Controller, HMSO, London, 1991.     

Analysis of fault tolerant computer systems

In many critical applications of digital systems, fault tolerance has been an essential architectural attribute for achieving high reliability. In recent years, the concept of the performability of such systems has drawn the attention of many researchers. In this paper we develop a general Markov model for fault tolerant computer systems. Various important performance measures, including the performability measures as well as some new performance measures, are treated in a unified manner. Furthermore, general and efficient computational procedures are developed for calculating these performance measures based on the uniformization technique of Keilson. A numerical example is given to illustrate the computational procedures developed.     

一种面向瞬时故障的容错技术的形式化方法

软件发生瞬时故障时,可能会导致处理器状态改变,致使程序执行出现数据错误或者控制流错误.目前已有许多软件、硬件以及混合的解决方案,主要的方法是重复计算和检查副本的一致性.但是,生成正确的容错代码十分困难,而且几乎没有关于证明这些技术的正确性的研究.类型化汇编语言(TAL)是一种标准的程序安全性证明的方式.本文概述了一种面向瞬时故障的软硬结合的容错方法,以及对该方法的形式化方法,包括容错类型化汇编语言、类型系统和容错定理.形式化的目的是为了验证,只有通过验证的程序代码才是类型安全的.本文只简单介绍了程序的形式化方法.     

基于FPGA的传感器故障诊断算法研究与实现

对于目前传感器设备故障诊断方法在诊断过程中会导致实际生产中弱故障诊断不灵敏,无法有效识别故障,并且充分考虑实际生产过程中的特点,提出基于FPGA的传感器故障诊断算法设计。在不同残差空间中分析故障,使系统对于弱故障诊断的精准性得到提高。使用迭代算法对主元分析算法模型进行更新,利用残差空间平方加权预测误差变量的重构对故障进行确定,从而对传感器故障进行在线诊断。最后,通过企业实际数据实现此方法的在线故障诊断实验。实验结果表明,此种方法能够有效诊断传感器设备故障。     

An improved sag detection approach based on modified Goertzel algorithm

Power quality is one of the key features in developing electric networks. It has been noticed because of its impact on economy and reliability of electrical networks. There are several power quality phenomena which are categorised in recent standards and literatures. Among them, voltage sag is more common and destructive for electric networks and consumers. This article presents a new detection method to monitor voltage sag in different electric network conditions. Goertzel algorithm is shown to be effective and simple for sag measurement compared to available sag detection methods.

In order to increase the detection speed and response time, the Goertzel algorithm is modified. This modification will add to the speed of sag detection. The feasibility of the proposed method is justified through a measurement set-up developed using the dSPACE R1104 Digital Signal Processor Platform. The experimental results prove that sag measurement speed is improved by twice using the proposed modified Goertzel algorithm in comparison with the original method and some established methods. The results also verify that the sag detection of the proposed method is not affected by harmonic distortion of the voltage waveform.     

Clos-based fault tolerant multicast ATM switch

A Clos-based fault tolerant multicast ATM switch is proposed in which each stage has one more redundant switch module. If one switch module is faulty, the redundant module replaces the faulty module. On the other hand, even under fault-free conditions, the redundant modules in the second and third stages will provide additional alternative internal paths, and hence improve the performance     

Bio-inspired fault tolerant network on chip

The integration of heterogeneous processing elements (PEs) or nodes in the System on Chip (SoC) has made the communication structure very complex. The bus based system between these components is not able to handle the communication requirements and, this has led to the idea of Network on Chip (NoC). The NoC addresses the communication requirement of different nodes on SoC. The physical sizes of devices in NoC are scaled down, including routers, processing elements and interconnects, giving rise to faults, system delay, and latency issues. Fault tolerant routing algorithms are used to recover from temporary faults while redundant resources (wires, routers) are required to overcome the permanent faults. These routing algorithms, however, still suffer from congestion problems, low bandwidth, and throughput utilization as well as lacking adaptivity and robustness. In this work, novel biologically inspired techniques were proposed for NoC using combined best effort (BE) and guaranteed throughput (GT) services. Moreover, the bio-inspired algorithms are compared and analyzed with each other using BE, GT and combined BE-GT services. The bio-inspired mechanisms of “synaptogenesis” and “sprouting” have been adopted in the proposed NoC algorithms and architecture. These techniques were implemented using the BE and GT services. With the help of these two bio-inspired techniques, the NoC becomes robust, fault tolerant and is able to efficiently utilize the throughput and bandwidth. The bio-inspired algorithms improved the accepted traffic (flit/cycle/node) by 38.99% compared to different techniques in the literature. The bio-inspired algorithm also improved the bandwidth and throughput utilization by 71.04% and 72.42% respectively compared to the XY and Odd-Even fault tolerant routing algorithms. Moreover, the bio-inspired algorithm had less end-to-end latency and interflit arrival time by 196.44% and 88.10% respectively compared to the literature techniques of XY and Odd-Even.     

抗差分功耗分析和差分故障分析的AES算法VLSI设计与实现

提出了一种抗差分功耗分析和差分故障分析的AES算法硬件设计与实现方案,该设计主要采用了数据屏蔽和二维奇偶校验方法相结合的防御措施.在保证硬件安全性的前提下,采用将128bit运算分成4次32bit运算、模块复用、优化运算次序等方法降低了硬件实现成本,同时使用3级流水线结构提高了硬件实现的速度和吞吐率.基于以上技术设计的AES IP核不仅具有抗双重旁道攻击的能力,而且拥有合理的硬件成本和运算性能.     

Stochastic analysis of a fault tolerant network system

This paper deals with a stochastic model related to a converter-based communication network system. In this model two converters are connected in parallel with a network system. Each converter has two failure modes—transient failure and latent failure. Transient failures occur due to minor faults in converters. Further the converter may enter into the latent failure mode if major hardware problems arise in the transient failure mode. The converter may recover automatically when it is in a transient failure mode and needs repair when it is in a latent failure mode. The system also enters preventive maintenance at random epochs when both converters are normal. System failure occurs when both the converters are in a latent failure mode. Using the regenerative point technique, various reliability measures are obtained.     

Reliability analysis of a fault tolerant computer system

This paper investigates a mathematical model of an information computer network system. In this model, the system has two parts—a controller and a terminal. It is also linked with a satellite by a disk antenna. Each part has two failure modes; one is transient failure and second is latent failure. After latent failure, the terminal is recoverable, but the controller is not recoverable. The system may also fail due to a common-cause failure when it is in the normal state or in a partially normal state. Failure rates are constant and recovery rates are general. Using the regenerative point technique several measures of system effectiveness are obtained.     

Architecture and reliability of fault tolerant bitonic sorter

Bitonic sorters are used in a number of telecommunication switching and digital signal processing systems, where any fault in the sorters may spell disaster. Unlike the conventional approach to enhance reliability using redundant sorters, the author presents a sorter with internal redundant sorting elements and evaluates its fault tolerance     

Reliability analysis of fault tolerant pipeline ring networks

In this paper the application of software implemented voting (ring structures) to pipeline networks is presented. The TMR characterization of the ring is extended to various topologies such as trees, cascade and locally voted pipelines. Both the aspects of reliability and data flow are analyzed in detail.     

Reconfigurable fault tolerant networks for fast packet switching

The authors consider the design and analysis of reconfigurable networks for fast packet switching. The design constraints resulting from the use of fast packet switching that affect fault-tolerant network design are carefully studied. A reconfigurable network with high link redundancy is then proposed. An abstract replacement model that characterizes the proposed reconfigurable network is presented. Network fault tolerance problems are transformed into well known assignment problems. Two practical designs based on feasible technology are presented. An appreciable reliability improvements is achieved and full bandwidth is maintained up to a tolerable level of failures, with relatively few spare switches