International audienceThe aim of this article is to present an experimental approach for studying the formation and transformation processes of archaeological fire structures. We present a synthetic review of our experimental project, which was developed in many different natural archaeological contexts. We report the results and problems associated with experimental fires lit on different kinds of soils and in different environments, followed by the observation of natural and anthropic transformations. Finally, we analyse the nature and significance of these results for the archaeological interpretation process, while describing some general trends and showing the complexity of the approach

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The results of a computational study on boiling channel stability are here discussed. The study compares the information obtained by two programs, developed in previous work for the linear and the nonlinear stability analysis of boiling channels basing on a simplified flow model, with the predictions of a well known system code. The phenomena highlighted by the results of the system code, adopted with different flow models and numerical methods, are discussed in a systematic way with the aid of the description obtained by the simplified model, in order to obtain a clearer picture than could be achieved by the mere application of the system code to conditions of interest for boiling water reactor stability. The effects on the obtained results of non-equilibrium, numerical discretization and number of nodes are considered, evaluating their influence on the predicted stability boundaries. Some physical aspects of the density-wave mode of instability are finally discussed basing on the predictions obtained by the different models.