Haiscam Abdallah received the B.S. degree in Mathematics from the libanese University, Lebanon, in 1983 and the Doctorat d'Universit\'e from the University of Rennes~I, France, in 1989. Since 1990, he is a Maitre de Conference (Associated Professor) in Computer Science at the University of Rennes II. His active research interests include dependability measures evaluation of critical computing systems and numerical analysis.
A well known method for obtaining the expected interval availability in the dependability analysis of repairable computing systems is the Standard Uniformization method. In this paper we develop a new method to compute the expectation of this interval availability. This new approach is based on the notion of the Uniformized Power technique and is well suited if the Markov chain is stiff and save computation time as long as the state space is not too large.