Embryonics: A Bio-Inspired Cellular Architecture with Fault-Tolerant Properties

This paper details and expands the work on Embryonics, a recently proposed fault-tolerant cellular architecture with reconfiguration properties inspired by the ontogenetic development of multicellular systems. The design of a selector-based embryonic cell, its applications and the reliability models associated to different embryonic reconfiguration strategies are presented. It is noted that embryonic distributed systems possess, in the majority of cases, better reliability characteristics than equivalent centralised systems.     

Partial-DNA cyclic memory for bio-inspired electronic cell

Genome memory is an important aspect of electronic cells. Here, a novel genome memory structure called partial-DNA cyclic memory is proposed, in which cells only store a portion of the system’s entire DNA. The stored gene number is independent of the scale of embryonic array and of the target circuit, and can be set according to actual demand in the design process. Genes can be transferred in the cell and the embryonics array through intracellular and intercellular gene cyclic and non-cyclic shifts, and based on this process the embryonic array’s functional differentiation and self-repair can be achieved. In particular, lost genes caused by faulty cells can be recovered through gene updating based on the remaining normal neighbor cells during the self-repair process. A reliability model of the proposed memory structure is built considering the gene updating method, and depending on the implementations of the memory, the hardware overhead is modeled. Based on the reliability model and hardware overhead model, we can find that the memory can achieve high reliability with relatively few gene backups and with low hardware overhead. Theoretical analysis and a simulation experiment show that the new genome memory structure not only achieves functional differentiation and self-repair of the embryonics array, but also ensures system reliability while reducing hardware overhead. This has significant value in engineering applications, allowing the proposed genome memory structure to be used to design larger scale self-repair chips.     

分布式控制系统的模型化可靠性分析方法

分布式控制系统（ＤＣＣＳ）是一种以通信网络为基本连接的多处理机控制系统。高可靠性和高可用性是ＤＣＣＳ系统的主要特点之一。在一些重要的过程控制应用中,为保证系统的高可靠性指标需要对分布式控制系统的可靠性分析与设计。本语在提出ＤＣＣＳ系统中的两个主要环节通信网络和智能化模块的可靠性数学模型基础上,讨论了ＤＣＣＳ系统的可靠性分析方法与一般设计步骤。     

冗余技术提高PLC控制系统可靠性的研究

针对工业现场对PLC控制系统可靠性提出更高的要求,提出利用冗余技术提高其可靠性。分析了硬件冗余和软件冗余在PLC控制系统中的应用,详细阐述了PLC控制器、输入输出口、通讯网络和电源各自的冗余方法,并着重以西门子300/400系列PLC为例进行了软硬件冗余的架构和原理分析。最后对冗余控制系统的可靠性进行分析,结果表明,使用冗余技术可使PLC控制系统的可靠性得到明显提高。     

A fault-tolerant multiprocess controller for magnetic bearings

A fault-tolerant microprocessor system designed to provide digital control for an active magnetic bearing is described. This particular control problem demands significant processing power, is easily divided into relatively independent parallel tasks, and cannot tolerate controller failures. The overall system requirements and architecture are described, as is the design of the digital control module and the analog I/O board. The fault tolerance of the system is evaluated. Extensive computer simulations of system reliability models verified that the design satisfies all of the reliability requirements. Although the system was designed for a specific problem, much effort was expended to make it general enough for applications to a wide range of real-time applications     

高可靠的计算机模块引导软件

在航天软件领域,为适应相关软件的快速发展与迭代,需要一种引导软件,使其能够对不同应用程序进行重构并保证其高可靠性. 本文基于SPARC架构设计并实现了一种引导软件,该引导软件既可以根据引导标识自动引导某个程序,又可以在地面指令控制下进行应用程序重构、引导等. 同时,采用三冗余架构、反弹墙、EDAC保护等可靠性措施,确保运行过程中的大多数软件错误能够得到恢复. 最终在计算机模块上进行测试,测试结果达到了预期目的.     

Reliable Differentiated Services Optimization for Network Coding Cooperative Communication System

Software-Defined Networking (SDN) is a new network architecture with flexibility and scalability, researchers introduced the core idea of SDN into wireless network, and a cooperative communication system based on network coding is proposed. In this paper, we carry on an investigation in differentiated service strategy of network coding cooperative communication system. The meaning of differentiated services is for the different applications take different power for data transmission and the transmission power is associated with their reliability needs. In other words, transmission power control is performed in the presence of known reliability, we named the scheme Reliability-Bounded Transmission Power Control (RTPC) scheme. The RTPC scheme changes the way in which all the applications in the past have been able to maintain the power to be transmitted, but the reliability requirements of different applications will be transmitted with different transmission power. In addition, because of the nodes that far away from the sink node still exist a lot of energy when the network died, so consider to improve the transmission power of non-hotpots nodes in order to increase the reliability of data transmission. The experimental results show that the RTPC scheme can greatly improve the transmission reliability without affecting the network lifetime.     

Software Reliability—Status and Perspectives

It is essential to assess the reliability of digital computer systems used for critical real-time control applications (e.g., nuclear power plant safety control systems). This involves the assessment of the design correctness of the combined hardware/software system as well as the reliability of the hardware. In this paper we survey methods of determining the design correctness of systems as applied to computer programs.     

Fault Tolerance in Continuous Process Control

Increasing the reliability of continuous process control systems means choosing a fault tolerance technique that matches computer hardware capabilities, as well as applications.     

LTRES: A loss-tolerant reliable event sensing protocol for wireless sensor networks

Many Wireless Sensor Network (WSN) transport protocols proposed in recent studies focus on providing end-to-end reliability as in TCP. However, traditional end-to-end reliability enforcement is energy and time consuming for common loss-tolerant applications in WSNs. In this paper, a Loss-Tolerant Reliable Event Sensing protocol (LTRES) is proposed based on the particular reliability requirements for dynamic event observation in WSNs. According to the application-specific requirements, a reliable event sensing threshold at the transport layer is determined by the sink. A distributed source rate adaptation mechanism is designed, incorporating a loss rate based lightweight congestion control mechanism, to regulate the data traffic injected into the network so that the reliability requirements can be satisfied. An equation based fair rate control algorithm is designed to improve the fairness among the traffic flows sharing the congestion path. The performance evaluations show that LTRES can provide event-based loss-tolerant reliable data transport service for multiple events with short convergence time, low loss rate and high overall bandwidth utilization.     

面向分布式实时仿真的应用层多播系统DVSCast

多播通信已经成为可缩放RT-DVS的一个重要支撑技术。针对IP多播部署的局限性和现有应用层多播系统的不足,本文提出了适用于分布式实时仿真的应用层多播系统DVSCast。DVSCast综合考虑了广域网组通信中的可靠性、时延争端到端的流量控制等需求,在层叠网路由算法、可靠多播和端到端的拥塞控制方面具有良好的可伸缩性,可支持大规模组应用。     

A Priority-aware Frequency Domain Polling MAC Protocol for OFDMA-based Networks in Cyber-physical Systems

Wireless networking in cyber-physical systems (CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliability constraints. One of the fundamental considerations for enabling CPS networks is the medium access control protocol. To this end, this paper proposes a novel priority-aware frequency domain polling medium access control (MAC) protocol, which takes advantage of an orthogonal frequency-division multiple access (OFDMA) physical layer to achieve instantaneous priority-aware polling. Based on the polling result, the proposed work then optimizes the resource allocation of the OFDMA network to further improve the data reliability. Due to the Non-polynomial-complete nature of the OFDMA resource allocation, we propose two heuristic rules, based on which an efficient solution algorithm to the OFDMA resource allocation problem is designed. Simulation results show that the reliability performance of CPS networks is significantly improved because of this work.      

SABUL: A Transport Protocol for Grid Computing

This paper describes SABUL, an application-level data transfer protocol for data-intensive applications over high bandwidth-delay product networks. SABUL is designed for reliability, high performance, fairness and stability. It uses UDP to transfer data and TCP to return control messages. A rate-based congestion control that tunes the inter-packet transmission time helps achieve both efficiency and fairness. In order to remove the fairness bias between flows with different network delays, SABUL adjusts its sending rate at uniform intervals, instead of at intervals determined by round trip time. This protocol has demonstrated its efficiency and fairness in both experimental and practical applications. SABUL has been implemented as an open source C++ library, which has been successfully used in several Grid computing applications.     

基于滑模观测器的永磁同步电机无传感器技术研究

永磁同步电动机（PMSM）具有体积小、效率高、可靠性高以及对环境适应性强等诸多优点,在各种高性能驱动系统中得到了广泛应用。永磁同步电动机无传感器控制技术不但能够降低系统成本,而且能够增加系统可靠性,是当前电机控制技术领域的研究热点之一。本文给出了一种基于滑模观测器的永磁同步电动机无传感器方法,通过观测器获取磁极位置和转速信息,并进行了矢量控制的仿真和实验研究,仿真和实验结果验证了无传感器算法的性能。     

差异化可靠传输拥塞控制算法

随着网络通信技术和应用的快速发展, 应用程序提出越来越精细化、差异化的数据传输性能需求, 然而传统网络传输协议较低的灵活性导致其无法满足各类应用的差异化需求, 亟需研究差异化的可靠传输控制协议以适应未来场景. 本文提出一种差异化可靠传输协议, 并重点提出一种基于可靠度的差异化可靠传输拥塞控制机制, 为不同的可靠度差值设计不同的拥塞避免和拥塞恢复策略, 并通过带宽估计策略精准调节拥塞阈值. 经实验验证, 差异化可靠传输拥塞机制在传输效率方面相比基于丢包和基于时延的拥塞算法有较大提升, 同时实现了良好的公平性.     

Dependable, intelligent voting for real-time control software

An intelligent and dependable voting mechanism for use in real-time control applications is presented. Strategies proposed by current safety standards advocate N-version software to minimize the effects of undetected software design faults (bugs). This requires diversity in design but presents a problem in that truly diverse code produces diverse results; that is, differences in output values, timeliness and reliability. Reaching a consensus requires an intelligent voter, especially when non-stop operation is demanded, e.g. in aerospace applications. This paper, therefore, firstly considers the applicable safety standards and the requirements for an intelligent voter service. The use of replicated voters to improve reliability is examined and a mechanism to ensure non-stop operation is presented. The formal mathematical analysis used to verify the crucial behavioural properties of the voting service design is detailed. Finally, the use of neural nets and genetic algorithms to create N- version redundant voters, is considered.     

DCCP partial reliability extension with sequence number compensation

Datagram congestion control protocol (DCCP), possessing congestion control and unreliable transmission, specially suits real-time multimedia applications. Nevertheless, losses of key packets will cause a substantial decline on quality of services (QoS) in some applications. This paper proposes a DCCP partial reliability extension (PR-DCCP) that can retransmit lost packets as needed. Since DCCP uses an incremental sequence number, the retransmitted packets cannot utilize their original sequence number. To solve this problem, PR-DCCP adopts sequence number compensation, which appends an offset to the retransmitted packet; thus the receiver can use the sequence number of this retransmitted packet and the attached offset so as to re-obtain the original sequence number. The simulation uses two performance metrics: decodable frame ratio (DFR) representing QoS, and useless data received ratio (UDRR) representing the bandwidth waste. These are used to evaluate different transport protocols, namely, PR-DCCP, DCCP, SCTP, TCP, and UDP. Simulation results show that PR-DCCP has the better DFR and UDRR than other transport protocols in almost all cases. For various movies, a DFR of PR-DCCP is 1.2–12.4% higher than that of DCCP; while UDRR is lower by 73.2–85.1%. Furthermore, two reliability policies to determine which packets require reliability are investigated. Finally, the comparisons between PR-DCCP and PR-SCTP are examined.     

基于CAN总线和组态技术的变电站监控系统

针对当前中小型变电站监控系统中存在的智能化、数字化程度不高和不便于远程控制等问题，利用CAN现场总线技术和组态监控技术，提出了一种低成本的变电站监控系统的构建方案。详细阐述了监控系统的软硬件设计。实践表明，该监控系统具有可靠性高、通信速度快、抗干扰能力强、组态灵活等优点，有着广泛的应用前景。     

Energy minimization for reliability-guaranteed real-time applications using DVFS and checkpointing techniques

This paper addresses the energy minimization issue when executing real-time applications that have stringent reliability and deadline requirements. To guarantee the satisfaction of the application’s reliability and deadline requirements, checkpointing, Dynamic Voltage Frequency Scaling (DVFS) and backward fault recovery techniques are used. We formally prove that if using backward fault recovery, executing an application with a uniform frequency or neighboring frequencies if the desired frequency is not available, not only consumes the minimal energy but also results in the highest system reliability. Based on this theoretical conclusion, we develop a strategy that utilizes DVFS and checkpointing techniques to execute real-time applications so that not only the applications reliability and deadline requirements are guaranteed, but also the energy consumption for executing the applications is minimized. The developed strategy needs at most one execution frequency change during the execution of an application, hence, the execution overhead caused by frequency switching is small, which makes the strategy particularly useful for processors with a large frequency switching overhead. We empirically compare the developed real-time application execution strategy with recently published work. The experimental results show that, without sacrificing reliability and deadline satisfaction guarantees, the proposed approach can save up to 12% more energy when compared with other approaches.     

活塞热疲劳试验装置的可编程控制器控制系统

介绍用可编程控制器与上位机械成的活塞热疲劳试验控制系统,具体介绍该系统的硬件配置和软件设计,该系统在实际应用过程中具有较高的可靠性。