Marked effect of imposed low frequency oscillations with amplitudes of 6.6 × 10−4−11.6 × 10−4 during creep of pre-aged Al-40 wt.% Zn alloy samples under constant stress at 423 K, was observed. Increasing the frequency or amplitude at a certain temperature, increased both n and ${\dot \varepsilon}_{\rm st}$ but decreased β values. The value of the ratio γ (0.75−0.77) shows the high dependence of the steady creep on the transient creep stage. The results were explained in view of the nature of the thermally induced structures during aging and their mode of interaction with lattice defects generated by the applied stress and the imposed oscillations. Grain boundary sliding and grain boundary diffusion of Zn and Al are suggested as the rate controlling mechanisms for both the transient and steady creep stages, respectively.

When the frequency of infrared light and the plasma frequency of highly doped n-GaAs are in resonance (e.g. for a doping concentration N = 7 × 1018cm−3 and a wavelength $\lambda=10.6 \mu$m), the free-electron induced optical nonlinearity is soundly pronounced. At such high doping concentrations it is necessary to extend the rigid quantum mechanical description of the free-electron induced nonlinearity to a multi-valley model. The central valley of GaAs was treated as a fully nonparabolic degenerated electron gas, whereas the satellite valley was modeled as an anisotropic electron gas of arbitrary degeneracy. The following intra- and intervalley absorption mechanisms were taken into account: impurity assisted, thermal and hot polar optical phonon assisted intravalley absorption on one hand and intervalley phonon assisted absorption in equivalent and nonequivalent intervalley absorption on the other hand. The dependence of the different absorption and energy relaxation mechanisms on the doping concentration, free electron heating, optical power density and the equivalent LL-intervalley deformation potential are discussed. We demonstrated for the first time that the behavior of the optical intervalley nonlinearity, i.e. the nonlinear absorption and nonlinear intervalley transfer, strongly depend on the equivalent LL-intervalley deformation potential. In the linear regime the model calculations are in good agreement with experimental results.

Synthesis of PZT solutions for thin films applications are realised either by sol-gel methods using reactive precursors or by MOD (metallorganic deposition) methods using heavy and/or hydrophobic precursors (applications: piezo or pyroelectric devices, integrated capacitors). Understanding these processes is difficult because of the complex chemistry of alkoxides. A specific MOD solution to produce PZT films is taken as an example to study the most important parameters influencing the behaviour of the final solution during deposition (spin coating) and subsequent thermal treatments. In this context a pilot reactor was developed in order to control and to measure this main parameters with the objective of a process optimization.

This paper deals with adaptive meshing in the case of time dependent problems within a 3D non linear multi-static approximation. In order to evaluate the numerical errors, the notion of ligurian is introduced. This estimator requires a couple of admissible fields. A method for the determination of this last couple is exposed. At least, on a three-phased transformer, we highlight the difficulties of the calculation of a well adapted error distribution for adaptive meshing. Three methods are exposed and compared.

Confocal Scanning Laser Microscopy (CSLM) in fluorescence mode was used to characterize microporous membranes. Two microfiltration membranes were investigated: a mixed ester (cellulose nitrate/cellulose acetate) 1.2 μm-rated membrane and a polycarbonate track-etched membrane with cylindrical pores of 2 μm diameter. Optical sections of the membranes stained with rhodamine and mounted in glycerol were performed at 1 μm intervals, from 0 to 10 μm. CSLM was found useful for microporous membrane characterization, as it gives some insight into bulk membrane morphology.

Electrostatic interactions of silver colloids with phospholipid monolayers at the air- water interface have been investigated by pressure-area measurements and fluorescence microscopy observations. It has been observed that the presence of silver particles in the subphase induces a change in the compression isotherms of phosphatidylglycerol, in particular in liquid-expanded LE / liquid-condensed LC phase transition. Condensed-phase domains show fractal-like shapes over colloids-containing subphases in contrast with rounded shapes observed over pure water. The effect of colloids on the compressibility was studied for different chain lengths and the change of the critical temperature was also determined. The comparison with the effect of monovalent salt was discussed since the charged colloids could be viewed as "multivalent" ions.

Trajectories of superparamagnetic sub-micronic particles submitted to a multi-force field are modeled numerically by a Finite Element Method. The first step is the computation of the magnetic forces and the carrier fluid velocity field, the second step is the computation of the trajectories using a Finite Difference Method with a predictor-corrector scheme.

Isolated cardiac cells stimulators design can be aided by numerical tools based on the behavior model. The linear model (RC circuit) is the most straightforward model for describing the electrical membrane cell behavior for an external electrical stimulation: however, an adjustment is necessary to make it competent to describe correctly the different types of excitation variability experimentally observed. A Linear Transient Model is presented, solved by the Finite Element Method.

Replication of patterns at a nanometer scale is a challenge for both advanced optical lithography and post-optical techniques. Considerable industrial effort has been devoted to the so-called leading-edge optical methods and the next generation lithography techniques. In parallel, a number of low-cost techniques such as nanoimprint and micro-contact printing are being investigated. In these methods, pattern replication is performed in non-conventional ways so that diffraction and scattering problems are no longer relevant. However, several other critical issues have to be studied. This paper describes two tri-layer pattern-transfer techniques, which can be used to improve the process latitude and the process compatibility. Pattern replication and lift-off transfer with feature sizes down to 30 nm and 150 nm have been achieved respectively by nanoimprint and micro-contact printing. As application examples, high-density magnetic dot structures are obtained and studied by measuring magneto-optical Kerr hysteresis loops.

An hybrid method combining two algorithms is proposed for the global optimization of inverted pattern functions encountered in non destructive control by eddy currents. This method performs first the exploration with a Genetic Algorithm, allowing to localize a "promising area" . Then the search is intensified inside that area, through a Nelder-Mead Simplex Search.