Mines ParisTech

About: Mines ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Microstructure. The organization has 6564 authors who have published 11676 publications receiving 359898 citations. The organization is also known as: École nationale supérieure des mines de Paris & École des mines de Paris.

Lyapunov design of stabilizing controllers for cascaded systems

Abstract: The design of a state feedback law for an affine nonlinear system to render a (as small as possible) compact neighborhood of the equilibrium of interest globally attractive is discussed. Following Z. Artstein's theorem (1983), the problem can be solved by designing a so-called control Lyapunov function. For systems which are in a cascade form, a Lyapunov function meeting Artstein's conditions is designed, assuming the knowledge of a control law stabilizing the equilibrium of the head nonlinear subsystem. In particular, for planar systems, this gives sufficient and necessary conditions for a compact neighborhood of the equilibrium to be stabilized. >

A phase field model incorporating strain gradient viscoplasticity: Application to rafting in Ni-base superalloys

Abstract: The first formulation of a phase field model accounting for size-dependent viscoplasticity is developed to study materials in which microstructure evolution and viscoplastic behavior are strongly coupled. Plasticity is introduced using a continuum strain gradient formalism which captures the size effect of the viscoplastic behavior. First, the influence of this size effect on the mechanical behavior of the material is discussed in static microstructures. Then, the dynamic coupling between microstructure evolution and viscoplastic activity is addressed and illustrated by the rafting of the microstructure observed in Ni-base superalloys under creep conditions. It is found that the plastic size effect has only a moderate impact on the shape of the rafts but is crucial to reproduce the macroscopic mechanical behavior of that particular material.

OES and FTIR diagnostics of HMDSO/O2 gas mixtures for SiOx deposition assisted by RF plasma

Abstract: A capacitively coupled radiofrequency PACVD process for SiO x deposition using oxygen-hexamethyldisiloxane (HMDSO) gas mixtures is characterised under a pressure of 1 Torr. Optical emission spectroscopy and FTIR absorption spectroscopy analyses are performed for different values of the dilution ratio X hm of HMDSO in oxygen. The power delivered to the plasma is set high enough (5 W/cm 2 ) to have a strong fragmentation of the monomer by electron impact. Two different regimes are then observed depending whether X hm exceeds or not 20 vol.%. Below this critical value, the monomer fragments are strongly oxidised. Above, densities of CO and CH 4 molecules strongly decrease. Trends observed in the evolution of the species concentrations as a function of X hm better agree the results by Aumaille et al. [K. Aumaille, C. Vallee, A. Granier, A. Goullet, F. Gaboriau, G. Turban, Thin Solid Films 359 (2000) 188] than those by Lamendola et al. [R. Lamendola, R. d’Agostino, F. Fracassi, Plasmas Polym. 2 (1997) 147] despite the pressure set in this work is closer to that used by the latter.

Minimum Spanning Forests for Morphological Segmentation

Abstract: Image segmentation in mathematical morphology is essentially based on one method: the watershed of a gradient image from a set of markers. We show that this watershed can be obtained from the neighbourhood graph of the initial image. The result of the segmentation is then a minimum spanning forest of the neighbourhood graph. Powerful interactive and very fast segmentation methods are derived