During the past Prague Conferences, the Organizing Committee had to face with a great regret permanent and even increasing delays in publishing the Transactions. The delays seemed to be out of any our reach as long as the traditional manuscript delivery rules and traditional printing technique were supposed to be employed. This is why we decided, starting with this Conference, for a new method of papers collection and printing. We want to thank all participants of our conference, in particular those who contributed to the volu- mes A and B, for understanding this our step. Our thanks are due to Academician Jaroslav Koieinik, the scien- tific editor of these volumes, and to the editorial board for re- viewing all papers and fulfiling many printing management duties. We also thank Academia Publishing House for printing the whole volume in time. ORGANIZING COMMITTEE of the EIGHTH PRAGUE CONFERENCE on INFORMATION THEORY, STATISTICAL DECISION FUNCTIONS, RANDOM PROCESSES PROBLEMES LIES A LA DETERMINATION DES SPECTRES DE PUISSANCE EN THEORIE DES FONCTIONS ALEATOIRES A. Blanc-Lapierre Gif-sur-Yvette (France) ~ La dll!termination exp~rimentale du spectre de pui,ssance, au sens physique, d'une grandeur fluctuante pose des probl~mes' d'analyse spectrale et d'ergodisme.Ces deux types de probl~mes sont examin~s conjointement pour une grandeur repr~sent~e par une fonction al~atoire X(t,~), pas n~cessairement stationnaire, mais pr~sentant des caract~res de permanence suffisants pour que la puissance moyenne puisse @tre difinie.
