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Friction behaviour is a critical factor in brake system design and performance. To describe the frictional behaviour as a function of the local conditions such as contact pressure, braking time, and sliding speed, it is more convenient to perform tribological investigations on a reduced-scale braking tribometer, if the surface thermal-loading encountered at full scale is effectively respected. Based on a discussion of scale factors, and on an analysis of heat flux and energies, various experimental conditions can be defined, respecting the same theoretical response in surface temperature. A series of simulating stop brakings from 140 km/h was conducted. It shows a very good correlation between predicted and experimental values. To cite this article: O. Roussette et al., C. R. Mecanique 331 (2003). [Copyright &y& Elsevier]

New tests and older ideas are explored to understand the origin of the pronounced contrast in lightning between land and sea. The behavior of islands as miniature continents with variable area supports the traditional thermal hypothesis over the aerosol hypothesis for lightning control. The substantial land–ocean contrast in updraft strength is supported globally by TRMM (Tropical Rainfall Measuring Mission) radar comparisons of mixed phase radar reflectivity. The land–ocean updraft contrast is grossly inconsistent with the land–ocean contrast in CAPE (Convective Available Potential Energy), from the standpoint of parcel theory. This inconsistency is resolved by the scaling of buoyant parcel size with cloud base height, as suggested by earlier investigators. Strongly electrified continental convection is then favored by a larger surface Bowen ratio, and by larger, more strongly buoyant boundary layer parcels which more efficiently transform CAPE to kinetic energy of the updraft in the moist stage of conditional instability. To cite this article: E. Williams, S. Stanfill, C. R. Physique 3 (2002) 1277–1292. [Copyright &y& Elsevier]

Nuclear fuel is the material in which the fission reactions occur. As such, it has to support many constraints induced by heat generation, fission product creation, as well as interaction with the coolant. These constraints are taken into account and fulfilled by the design. However, during irradiation, many changes are known to occur. Among them, irradiation damage, OD oxidation and changes in chemical or physical characteristics are to be considered. In addition, intermediate storage adds new constraints that the fuel has to support. With emphasis on the water reactor fuels, by far the most important group, a review will be given of major points, focusing on a few specific areas. To cite this article: C. Lemaignan, C. R. Physique 3 (2002) 763–772. [ABSTRACT FROM AUTHOR]