Past Research

2003 Research

by Dr. Janusz Zalewski

Programming languages for use in safety-related applications

W. Halang, J. Zalewski

Annual Reviews in Control, Vol. 27, No. 1, pp. 39-45, 2003.

Abstract: Programmable electronic systems are being used in almost all application sectors to perform non-safety and increasingly to perform safety functions as well. Although software-based solutions are usually superior to hardwired ones for reasons of efficiency and flexibility, there is a certain reluctance of the certification authorities when it comes to licensing computer-based systems which are classified as safety critical. Despite many attempts to overcome problems of software safety (IEC 61508, IEC 880, VDE 0801, IDS 00-55, RTCA/DO-178), up to now neither precise guidelines supporting the software development process are available, nor are there serious efforts being made to develop programming languages dedicated to the implementation of safety critical functions. To improve this unsatisfactory situation, i.e. to meet both economic and safety requirements, it is necessary to design appropriate language concepts with consequent regard to safety aspects. Accordingly, four subsets of a real time language suitable for the implementation of safety-related systems are proposed, whose definitions fulfil the respective requirements of the four safety integrity levels.

Considering Local Bus Traffic in Network Performance Simulations

V. Jonnalagadda, M. Mathure, A. Kornecki, J. Zalewski

Proc. CNDS'03 Communication Networks and Distributed Systems Modeling and Simulation Conference, Orlando, FL, January 19-23, 2003, pp.109-114

Abstract: In a large distributed computing environment based on local area networks, such as Ethernet or FDDI ring, system performance may be significantly degraded by a bottleneck at some segment of a particular network. In this study we examine the effect that local bus traffic has on the overall performance of a network. In particular, we studied server access for networks using two interconnect technologies, VMEbus and RACEway. The results show that local bus traffic on the CSMA/CD or FDDI LAN backbones has a significant impact on overall performance and may decrease access delays by an order of magnitude, or more, depending on traffic load.

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