Showing papers on "Dependability published in 1986"

Dependable computing: From concepts to design diversity

Abstract: This paper is composed of two sections. The first provides a conceptual framework for expressing the attributes of what constitutes dependable and reliable computing: a) the impairments to dependability (faults, errors, and failures), b) the means for dependability (fault avoidance, tolerance, removal, and forecasting), and c) the measures of dependability (reliability, availability, safety). The second section focuses on one of the most challenging problems for dependable computing: coping with design faults.

A Multi-Microprocessor Based Travelling Wave Relay - Theory and Realization

Abstract: A new travelling wave digital protection scheme to be used as an ultra high speed (UHS) EHV/ UHV transmission line relay is presented in this paper. Some of the potential problems and limitations associated with other travelling wave schemes are avoided. Verification of the relay operating principles is presented through digital computer numerical simulation using an electromagnetic transients program (EMTP) in conjunction with simulation of the proposed algorithm. Parallel digital processing is incorporated through multi-microprocessor implementation. Hardware and software of a multiprocessor prototype are managed in a way to fit the algorithm requirements in as simple a construction as possible. The resulting scheme achieves significantly improved security and dependability, in addition to the main features: fault classification and UHS phase selection in selective-pole schemes with minimum communication between the protected ends.

On the multilateral index number system based on the factorial approach

Abstract: This paper examines what of the Eichhorn-Voeller axioms are satisfied by the multilateral index numbers based on the factorial approach. Finally, concerning the overall performance of the system, a pertinent observation is made strengthening its dependability as a practical guide.

Dependability evaluation of parallel/distributed computer networks

Abstract: As a result of the proliferation of low cost off-the-shelf microprocessors and the advances in networking technology, parallel/distributed computing has become increasingly popular. Parallel systems are broadly divided into two categories depending on the type of interconnection topology. These are called "multiprocessor" systems and "multicomputer" systems. At the system level, a multiprocessor or multicomputer consists of two subsystems. One subsystem is the computation facility which is provided by processors and memories. The second subsystem is the communication network used to support interprocessor communication. These two components are equally important in a parallel processing environment. Any failure of a component in these subsystems results in performance degradation of the system. This dissertation deals with the dependability evaluation of multiprocessor and multicomputer architectures and their behavior with graceful degradation. Three dependability measures, known as reliability, performance availability (PA), and maintainability, are used to evaluate and characterize various parallel architectures. These measures are based on the system requirements for the parallel execution of a task (job) which consists of a number of subtasks. This research effort differs from the most previous ones in that methods for incorporating the degradation of the communication network into system model are addressed. In the sequel, we present two different models; one is known as the bus oriented model (BOM) and the second one is known as the switch oriented model (SOM), for analyzing the reliability and bandwidth availability (BA) of various multiprocessors. The BOM is an analytical model whereas the SOM is a simulation technique. The SOM captures the communication network representation more accurately. A simulation model is presented to evaluate the reliability and computation-communication availability (CCA) of all types of multicomputer networks suggested in the literature. Mathematical models are presented for the on-line and off-line maintenance of both types of parallel systems. First, the effect of on-line maintenance processor reliability on the system dependability is addressed. Second, models for system downtime and cost are developed for three types of off-line maintenance policies known as scheduled maintenance (SM), unscheduled maintenance (UM), and scheduled and unscheduled maintenance (SUM).

Safety of computer control systems 1986 (Safecomp '86) : trends in safe real time computer systems : proceedings of the Fifth IFAC Workshop, Sarlat, France, 14-17 October 1986

Abstract: (partial) Software Quality Assurance: Some thoughts on software quality assurance, K Fruhauf. Quantitative assessment of safe and reliable software, B Runge. Modelling system quality, A A Kaposi & B A Kitch nham. Programmable electronic systems safety: standards and principles, S R Nunns et al . Software Fault Tolerance: A recovery block model and its analysis, S D Cha. Diversity - some considerations about its benefits and limitations, F Saglietti & W Ehrenbe ger. Error recovery in multi-version software, K S Tso et al . Multi-version software development, J P J Kelly et al . Fault-Tolerant Distributed Systems: The joint algorithm: ordering messages in replicated systems, L Mancini & G Pappala do. Protection of shared resources, F Malabocchia & L Simonci i. A proposal for distributed commitment and abort of multi-site transactions in a multi-microprocessor system, P Ancilotti et al . Safe and Reliable Architectures: Self-checking circuits: from theory to practice, M Nicolaidis & B Courtoi . Knowledge Based Approach to Safety: Data base coherence: LRC language commutative convergence, J-F Hery & J C Laleu . Man-Machine Interface: Toward fault-tolerant man-machine interfaces, R A Maxion. Design for Safety: Engineering software safety, W J Quirk. Reliability and Safety Assessment: Dependability prediction: comparison of tools and techniques, M Mulazzani & K Trivedi Test and Qualification: Basic qualification concepts for instrumentation and control systems, F A Monaco. Author index. Subject index.