Low-cost fault tolerance in evolvable multiprocessor systems: a graceful degradation approach

The evolvable multiprocessor （EvoMP）, as a novel multiprocessor system-on-chip （MPSoC） machine with evolvable task decomposition and scheduling, claims a major feature of low-cost and efficient fault tolerance. Non-centralized control and adaptive distribution of the program among the available processors are two major capabilities of this platform, which remarkably help to achieve an efficient fault tolerance scheme. This letter presents the operational as well as architectural details of this fault tolerance scheme. In this method, when a processor becomes faulty, it will be eliminated of contribution in program execution in remaining run-time. This method also utilizes dynamic rescheduling capability of the system to achieve the maximum possible efficiency after processor reduction. The results confirm the efficiency and remarkable advantages of the proposed approach over common redundancy based techniques in similar systems.     

Fork-Join program response time on multiprocessors with exchangeable join

INTRODUCTION With the prevalence of distributed computing and parallel programming languages (Barry and Allen, 1998), performance evaluation of the parallel execu-tion systems becomes important. In this work we derive bounds and an approximation of the mean response time of a particular type parallel program: program with Fork-Join tasks and executed in multi-processor with first come first served (FCFS) policy. This kind of program is general in large-scale simu-lation and numerical …     

Joint channel and power allocation scheme for cognitive wireless networks

Cognitive radio (CR) is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users (CUs) are allowed to use the radio spectrum concurrently with the primary users (PUs) under the interference temperature constraint. We investigate the system performance by using the proposed joint channel and power allocation scheme under two transmit strategies to achieve higher data rates and performance diversity gain respectively. Simulation results show that the proposed scheme provides a significant improvement on the bit error rate (BER) performance and spectrum efficiency of a cognitive wireless network.     

Optimizing pipeline for a RISC processor with multimedia extension ISA

INTRODUCTION Embedded real-time multimedia applications that involve processing of video and audio streams de- mand an efficient media approach. A thorough survey of media approaches and architectures was given by Dasu and Panchanathan (2002). These media proc- essing architectures can be classified into three cate- gories including dedicated (application-specific) hardware, media processors and instruction set ar- chitecture extensions for general-purpose processors. As for embedded med…     

对RSA密码系统旁路攻击的防御

Based on the structure of the side channel attacks (SCAs) to RSA cryptosystem can resist the fault attack andcombine with the randomization method for the message and secret exponent, a new implementation scheme of CRT-based(the Chinese remained theorem) RSA is proposed. The proposed scheme can prevent simple power analysis (SPA), differentialpower analysis (DPA) and time attack, and is compatible with the existing RSA-CRT cryptosystem as well. In addition, animprovement for resisting fault attack is proposed, which can reduce extra computation time.     

Support Vector Machine for mechanical faults classification

INTRODUCTION Support Vector Machine (SVM) is a relativelynew soft computing method based on statisticallearning theory presented by Vapnik (1995). In SVM,original input space is mapped into a high dimen-sional dot product space called feature space in whichthe optimal hyperplane is determined to maximize thegeneralization ability of the classifier. The optimalhyperplane is found by exploiting a branch ofmathematics, called optimization theory, and re-specting the insights provided by …     

DX-600KW全固态中波发射机新音频控制板故障分析与解决

DX-600KW中波发射机TCU机柜中的音频控制板作为各PB单元的音频总处理者,其板上所出的故障将同时影响各PB单元的音频通路。文章主要对新音频控制板中从音频输入开始,到其被由音频选择矩阵分配给各个PB单元的工作原理进行分析,并介绍一种该板引起的常见故障,此故障近来也在各台出现过。现把我台的改进方案总结出来,希望能为广播发射战线的同仁提供参考和帮助。     

Batch process monitoring based on multilevel ICA-PCA

In this paper, we describe a new batch process monitoring method based on multilevel independent component analysis and principal component analysis （MLICA-PCA）. Unlike the conventional multi-way principal component analysis （MPCA） method, MLICA-PCA provides a separated interpretation for multilevel batch process data. Batch process data are partitioned into two levels： the within-batch level and the between-batch level. In each level, the Gaussian and non-Gaussian components of process information can be separately extracted.I^2 T^2 and SPE statistics are individually built and monitored. The new method facilitates fault diagnosis. Since the two variation levels are decomposed, the variables responsible for faults in each level can be identified and interpreted more easily. A case study of the Dupont benchmark process showed that the proposed method was more efficient and interpretable in fault detection and diagnosis, compared to the alternative batch process monitoring method.     

使用试错法加快扩频通信伪随机码捕获

An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum （DSSS） receivers is proposed and analyzed in this paper. The system consists of two major parts： a phase region estimator and a phase alignment detector. We use an auxiliary sequence to correlate the incoming signal in the phase region estimator. Since the cross-correlation value between the auxiliary sequence and the incoming PN signal has linear magnitude, and can provide the direction for the phase updating, an optimum search algorithm, try and error method, can be adopted to obtain the phase region information of the incoming signal. The mean acquisition time is derived through the signal flow graph theory. The time is compared with that of the conventional serial search scheme, and the results show that the proposed scheme can achieve coarse acquisition significantly faster than the conventional scheme.     

基于多核处理器的程序性能优化方法

多核处理器即在一个处理器芯片上集成多个处理器核心,可同时执行多个线程。虽然多核处理器中每个核的时钟频率没有增加,但多个核的并行处理提供了远比单核强大的计算能力,同时,也大大提高了CPU的设计复杂性,基于现代处理器的设计技术,结合程序的实现过程,探讨优化程序性能的几种方法,提升程序编写质量,提高执行效率。     

基于热释电传感器的红外火焰探测系统的研究

针对感烟、感温等火灾探测器探测距离短,响应速度慢,易受到外界信号干扰导致误判和漏判等问题,提出了一种基于热释电火焰传感器和数字信号处理实现方案．系统以dsPlC33FJ64GP802处理器作为核心构建信号处理平台,信号先通过预处理电路隔直,滤波,放大处理之后通过数字信号处理系统,采用IIR数字滤波器滤除干扰信号,再进行FFT运算,将信号由时域转换到频域,计算出信号在各个频段的能量值,通过分析火焰信号的时域与频域,实现对火焰信号的准确判断．基于本设计方案的火焰探测器,可以通过适当增加光学组件改变探测距离,并能实现远距离火焰探测．这在大空间自动消防水炮设计、森林防火等领域具有广阔的应用前景．试验证明,本系统达到了预期的效果．     

软件坚固性与基于软件的容错技术

坚固性是软件可靠性的主要方面之一，并正在成为衡量软件质量的重要指标。基于软件的容错技术是实现软件系统坚固性的主要途径，包含了操作容错、数据容错、软件容错和硬件容错四个方面内容，其本质都是冗余方法，基本手段的故障检测与故障定位、故障包容与故障屏蔽、系统重构与故障恢复等，软件容错的基本方法是多样性设计，其代表性方法是恢复块RB和多版本编程NVP技术。本文同时简要介绍了容错技术的基本思想、方法及相关研究的发展概况。     

Forward and backward models for fault diagnosis based on parallel genetic algorithms

In this paper, a mathematical model consisting of forward and backward models is built on parallel genetic algorithms （PGAs） for fault diagnosis in a transmission power system. A new method to reduce the scale of fault sections is developed in the forward model and the message passing interface （MPI） approach is chosen to parallel the genetic algorithms by global single-population master-slave method （GPGAs）. The proposed approach is applied to a sample system consisting of 28 sections, 84 protective relays and 40 circuit breakers. Simulation results show that the new model based on GPGAs can achieve very fast computation in online applications of large-scale power systems.     

Reliable energy-efficient routing with novel route update in wireless sensor networks

In this paper we introduce a novel energy-aware routing protocol REPU （reliable, efficient with path update）, which provides reliability and energy efficiency in data delivery. REPU utilizes the residual energy available in the nodes and the received signal strength of the nodes to identify the best possible route to the destination. Reliability is achieved by selecting a number of intermediate nodes as waypoints and the route is divided into smaller segments by the way-points. One distinct advantage of this model is that when a node on the route moves out or fails, instead of discarding the whole original route, only the two way-point nodes of the broken segment are used to find a new path. REPU outperforms traditional schemes by establishing an energy-efficient path and also takes care of efficient route maintenance. Simulation results show that this routing scheme achieves much higher performance than the classical routing protocols, even in the presence of high node density, and overcomes simultaneous packet forwarding.     

基于IDEA加密网络的密钥管理策略

文主要介绍了基于IDEA(Internation Data Encryption Algorithm)加密方法的网络中一种密钥分配方案。它将整个网络系统中的密钥不会以明文的形式出现进行传送,而是以被高级密钥加密的形式传输和保存。从而较好的提供了一种安全稳定的密钥管理方案。     

Gradual refinement for application-specific MPSoC design from Simulink model to RTL implementation

The application-specific multiprocessor system-on-chip （MPSoC） architecture is becoming an attractive solution to deal with increasingly complex embedded applications, which require both high performance and flexible programmability. As an effective method for MPSoC development, we present a gradual refinement flow starting from a high-level Simulink model to a synthesizable and executable hardware and software specification. The proposed methodology consists of five different abstract levels： Simulink combined algorithm and architecture model （CAAM）, virtual architecture （VA）, transactional accurate architecture （TA）, virtual prototype （VP） and field-programmable gate array （FPGA） emulation. Experimental results of Motion-JPEG and H.264 show that the proposed gradual refinement flow can generate various MPSoC architectures from an original Simulink model, allowing processor, communication and tasks design space exploration.     

Autonomous optimal coordination scheme in protection system of power distribution network by using multi-agent concept

A protection system using a multi-agent concept for power distribution networks is pro- posed. Every digital over current relay(OCR) is developed as an agent by adding its own intelli- gence, self-tuning and communication ability. The main advantage of the multi-agent concept is that a group of agents work together to achieve a global goal which is beyond the ability of each individual agent. In order to cope with frequent changes in the network operation condition and faults, an OCR agent, proposed in this paper, is able to detect a fault or a change in the network and find its optimal parameters for protection in an autonomous manner considering information of the whole network obtained by communication between other agents.Through this kind of coordi- nation and information exchanges, not only a local but also a global protective scheme is com- pleted. Simulations in a simple distribution network show the effectiveness of the proposed protec- tion system.     

Experimental Research on Single-Pass SHG from Periodically Poled LiNbO3 Crystal

Quasi-phase-matching(QPM) periodical poled LiNbO3 （PPLN） is designed and successfully fabricated to enable second harmonic generation (SHG),The samples were Z-cut 0.5 mm thick and grating period is A=6.8 μm for the first order QPM of contimual wave λ=1.064μm which is emitted by Nd:YAG laser at room temperature 27℃,The output single-pass SHG power was tested by an authorized optical system.The normalized max conversion efficiency is calculated to be 0.25% (W.cm)^-1,The fabrication and parameters calculated method are introduced,and testing scheme is described in this paper,Even some ideas to improve conversion efficiency are offered.     

Performance of the geometric approach to fault detection and isolation in SISO, MISO, SIMO and MIMO systems

In this paper,a geometric approach to fault detection and isolation (FDI) is applied to a Multiple-Input Multi-ple-Output (MIMO) model of a frame and the FDI results are compared to the ones obtained in the Single-Input Single-Output (SISO),Multiple-Input Single-Output (MISO),and Single-Input Multiple-Output (SIMO) cases. A proper distance function based on parameters obtained from parametric system identification method is used in the geometric approach. ARX (Auto Regressive with eXogenous input) and VARX (Vector ARX) models with 12 parameters are used in all of the above-mentioned models. The obtained results reveal that by increasing the number of inputs,the classification errors reduce,even in the case of applying only one of the inputs in the computations. Furthermore,increasing the number of measured outputs in the FDI scheme results in decreasing classification errors. Also,it is shown that by using probabilistic space in the distance function,fault diagnosis scheme has better performance in comparison with the deterministic one.     

提高计算机网络可靠性的方法研究

文章阐述了计算机网络可靠性的影响因素、原则以及现状。在此基础上分析了提高计算机网络可靠性的方法:即容错性的设计方案,双网络结构设计方案,整体网络体系设计方案,构建层次布局的设计方案,延长整个网络的寿命周期和应加强对网络管理监控。