Finite element error bounds for a curve shrinking with prescribed normal contact to a fixed boundary

We approximate the evolution of a curve subject to motion bycurvature by linear finite elements. The curve evolves insidea given domain and meets orthogonally. We derive optimal boundsfor the error with respect to the L²- and H¹-norms and presentsome computed examples.     

Comparison between methods of generation of waveriders derived from conical flowsComparaison de méthodes de génération de waveriders derivés d'écoulements coniques

Waveriders are supersonic or hypersonic lifting configurations which are generated from a known flowfield, preventing leakage from the high-pressure undersurface to the uppersurface, and allowing high lift-to-drag ratios. A method based on an Euler code is used to study waveriders generated from the flow field around axisymmetric bodies. In the case of a cone, the results are compared with those given by the Taylor–Maccoll system and inviscid hypersonic small-disturbance theory. In the present study conditions at Mach 5, the last method paradoxically works at high cone angles (greater than 10°) while the best lift-to-drag ratio are obtained with small angles. To cite this article: B. Mangin et al., C. R. Mecanique 334 (2006).     

Magnetism in amorphous Fe-Si alloys

Fe-Si alloys have been obtained by the vapor quenching technique. Resistance measurements, electron microscopy and diffraction results are typical of an amorphous system. The Mössbauer spectra of these amorphous alloys, fitted in terms of a distribution of hyperfine fields, show the existence of a local magnetic order with, however, a proportion of weakly or even no coupled Fe atoms which is temperature and Fe-concentration dependent.