Considering the chemical free energy as a the nonlinear function of temperature, a relationship between temperature and the martensitic volume fraction associated with austenite-martensite phase transformation has been obtained theoretically and compared with experimental results in some iron-based alloys.

A quantitative comparison of the errors introduced by several methods for the reproduction ofthe crystallographic orientation distribution function from poles figures is presented. The harmonic,ADC, WIMV and component methods have been employed in the characterization of the deformation and recrystallization textures of a Fe-50% Ni alloy in order to investigate the accuracy associated with each one of these methods. To carry out this study, experimental and synthetic pole figures have been used as input data. The strong and weak points of each method are examined showing that the iterative discrete methods (ADC and WIMV) are better suited for the reproduction of the texture function in the present case. In comparing these two discrete methods, it is evidenced that the ADC method reproduces more accurately both the experimental and synthetic texture functions over the entire range of texture sharpness considered.

Dielectric response of PLZT(x/65/35) ceramics (with x = 0, 2, 4, 5) was studied using radio frequency and microwave techniques in the temperature range 300−900 K and with a frequency range of 102 Hz-3 × 109 Hz. Dielectric relaxation appears around 1 × 109 Hz at room temperature. The relaxation frequency softens at T c and the dielectric relaxation exists in both paraelectric and ferroelectric phases and depends on x the lanthanum concentration. A model of correlation chains gives some keys for understanding the frequency behaviour of such materials.

In this paper, we study a new kind of continuous-alternating converters: a seven-level neutralpoint clamping (NPC) voltage source inverter (VSI). We propose this inverter for applicationsin high voltage and high power fields. In the first part, we develop the knowledge and the control modelsof this inverter using the connections functions of the semi-conductors. After that, we present two pulsewidth modulation (PWM) algorithms to control this converter using its control model. We proposethese algorithms for digital implementation. This multilevel inverter is associated to the inductionmachine. The performances obtained are full of promise to use it in the high voltage and high powerfields of electrical traction.

This paper presents a flexible numerical technique which is especially suited to analyze lateral modulation of quantum effects in short channel MOS transistors. We discuss boundary conditions for the Schrödinger equation and the impact of the finite element meshing. We show how channel length shortening alters the sub-band structure, thus giving an evaluation of the limits of a 1D quantum approach.

This paper is aimed at the modelling of an electrical discharge controlled by mean of adielectric barrier, at atmospheric pressure; we focus our study on the homogeneous“regime”. This model is based on the use of equivalent electrical circuits and is takinginto account the main phenomena of the discharge. We also offer a method for thedetermination of the parameters of the model; the comparison of the experimental waveformswith the simulated ones is validating the accuracy of the proposed model in the case ofdischarges in nitrogen or helium. Our model is exploited to point out the drastic importanceof the electrical characteristics of the power supply with respect to the mainwaveforms of the discharge.(includingcomputer-aided circuit design and analysis)

Meshless methods are new numerical simulation methods. Meshless methods are based on a simple set of nodes that has to be optimizedto obtain a good convergence of the approximation.For these reasons, in this paper, we have developed a new procedure in orderto generate the initial set of nodes. This approach does not rely on any existing meshing technique, such as Delaunay or advancing front. It is based on a map density of nodes and a regularization procedure.

A virtual NC − AFM machine has been built using the Matlab language. The virtual NC − AFM is identical to a real hybrid machine built with Digital Instruments and Omicron blocks. Therole of every subset is described in detail, and special attention is paid to the parameters of theAutomatic Gain Control (AGC) which controls the amplitude of the oscillations. The virtual machine isa powerful tool, that allows to solve, without any approximation, non linear coupled differentialequations describing the physics of the tip-surface interaction. The machine is then used to study thefrequency shift and damping signal in the approach-retract mode. Two types of situations are analyzed: thefirst one corresponds to the case where no dissipative force is introduced in the tip-surface interaction,the second one deals with dissipative forces. These last ones are here introduced by assuming a mechanicaldeformation of the surface under the tip. Interesting results are then obtained, in particular the factthat unstability may occur under some particular conditions. Most of the results obtained by simulationare then compared with those of analytical models already published in the literature.

We developed a very-low temperature scanning tunneling microscope (STM) working at 60 mK in a dilution refrigerator. It features both atomic resolution and micron-sized scanning range at low temperature. High-resolution spectroscopy of superconducting samples at a measured temperature of 60 mK are presented.