Thomas Raith

Performance analysis of finite capacity polling systems with nonexhaustive service

Abstract In performance investigations of token passing local area networks, communication subsystems in switching systems with distributed control, etc., the class of polling models, i.e., multiqueue systems with cyclic service, is often employed. This paper presents an approximate analysis method for this class of models, whereby realistic modelling assumptions like the finiteness of queue capacities and nonsymmetrical load conditions are taken into account. The method of imbedded Markov chain is used for the analysis, whereby the special case of exponential as well as the case of general service time are successively considered. The latter case is analyzed in conjunction with a moment matching approach for the cycle time. The validation of the approximation is done by means of computer simulations. Numerical results are shown in order to illustrate the accuracy of the calculation method and its dependency on system parameters.

Specification and design of electronic control units

Electronic control units (ECU) play a more and more important role in the development of road vehicles. Forecasts lead up to 25% of the total vehicle value in 2000. The increasing complexity and stringent quality and cost requirements mandate tremendous improvements in the specification and design process. This paper presents the cooperative activities at Daimler-Benz research and Mercedes-Benz development departments to install an optimized design process.

Serielle Datenbussysteme im Kraftfahrzeug

Der Einsatz elektronischer Systeme mit zunachst eng abgegrenzten Einzelfunktionen hat zum Ziel, den Fahrer bei der Fuhrung seines Fahrzeuges wirksam zu unterstutzen, zu entlasten und storende bzw. unerwunschte Einflusse von ihm fern zu halten. Das wachsendes Leistungspotential der Elektronik erfordert ein gesamtheitliches und durchgangiges Systemkonzept der Fahrzeugelektronik. Serielle Datenbussysteme ermoglichen durch Multi-plextechniken den Informationsaustausch zwischen raumlich zentral und dezentral angeordneten Komponenten im Fahrzeug, verbunden mit hoher Flexibilitat (Nachrustung oder Weiterentwicklung einzelner Komponenten).