This paper proposes a new process of temperature measurement of a material or object at microwave frequencies. This process allows self-balancing of the temperature measurement system and takes into account any mismatching between the antenna and the radiating object. The process uses a temperature sensor based on a monolithic integrated circuit. A theoretical and experimental study is conducted to test this process.

We α present and demonstrate a method to determine the refractive index and absorption changes in a two mode fiber interferometer. Measurement on the 632 nm transitions in Er3+ silica fiber shows that refractive index and absorption changes result from ground and excited state transitions respectively. The GSA/ESA cross-sections ratio was found to be 14.

We have accelerated the ageing of CuAlS2 by the application of a static electrical field for different degradation times. We have investigated the admittance spectroscopy and the scanning electron microscopy to follow and understand the (mass-charge) coupled transport processes produced in the volume and on the surface of these films. The electrical constraint induces, after an incubation phase, an activated decrease of the resistance, followed by a susbstantial increase correlated to the formation of an open circuit. This degradation occurs more rapidly for the films having initially a lower resistance, due to the thermal dissipation which increases considerably the temperature to about 140 °C. Admittance spectra reveal, at low frequencies, a capacitive loop related to the formation of a charge space induced by copper diffusion. Such migration develop induces the formation of copper arborescences, spreading from the cathode towards the anode. The effect of these structures on the properties of the degraded films is discussed in relation to electromigration and associated processes (whiskers, fracture, healing, bridge-building, ...). Also, we have noticed their similarity with fractal phenomena such as electrodeposition and dielectric breakdown.

Planar metal/semiconductor/metal (PMSM) junctions buried in a SiO2 layer are fabricated using electron beam lithography on a silicon sample. A technique of jump of pixels is used to obtain different sizes of junctions, the smallest having an inter-electrode distance of 5 nm. The current-voltage characteristics and the variation of the junction conductance with the temperature down to 8 K have been studied. At all sizes and for both polarities, the I−V curves correspond to the reverse characteristic of a metal/semiconductor contact. At low bias voltage, the influence of a thin insulator interfacial layer between the metal and the semiconductor has been pointed out. For these junctions, a non-linear low voltage I−V characteristics is observed before the large voltage thermionic emission regime. For the smallest junctions obtained without interfacial oxide layer, a linear I−V characteristic is recovered at low voltage. Their conductance can be lowered by decreasing the temperature.

Microscale phenomena between the surface of chemically vapour deposited silicon films and a silicon nitride tip was investigated using Scanning Force Microscopy. An analysis of friction forces for different scan directions is presented. For different applied forces, the friction forces were measured and consequently the friction coefficient was calculated. We found that the average friction force linearly increases with the applied force and is reversible when unloading. Connection between the surface roughness and the friction coefficient was experimentally demonstrated.

We have studied the effect of the substrate on the structural and electrical properties of Ni thin films. Series of Ni thin films have been prepared by dc diode sputtering on four different substrates, glass, Si(111), Si(100) and mica; the Ni thickness ranges from about 47 nm to 317 nm. We observed that Ni grown on glass has no texture. On the other hand Ni deposited on Si gets the 〈111〉 preferred orientation for all samples, even the thinner ones. Grain sizes were found to increase with increasing thickness for Ni/glass and Ni/Si(100), with the grains in Ni/Si(100) much larger than the corresponding ones for Ni on glass. The lattice constant of Ni on glass is smaller than that of the bulk. For the Ni on Si, however, the lattice constant is practically equal to the bulk value. We noted that the resistivity ρ decreases with increasing thickness and with increasing grain size for practically all samples. Also the Ni thin films deposited on a semiconductor substrate (Si(100) and Si(111)) get a higher resistivity than Ni on an insulator (Ni/glass for example) for the same Ni thickness. No magnetoresistance was observed in these Ni thin films at ambient temperature and for about a half kOe perpendicular magnetic field. These experimental results will be interpreted and discussed.

The deposition of the ternary compound Ti-N-Si using the cold-wall CVD technique from TiCl4-NH3-SiH2Cl2 presents difficulties because of undesired powder formation in the gas-phase. For a better understanding and control of the mechanism, both simulation and experiments have been carried out to determine favorable conditions to minimize the undesired adducts. First, an original technique has been developed for the reactive injection with a double-passage nozzle specially designed. Then powders have been deliberately grown at different conditions, with their chemical compositions analyzed using X-ray diffraction spectra. Further, the flow has been modeled and compared with the results provided by means of laser sheet visualization. It is shown that the powders can be avoided with some special reactive injection schemes and by controlling the nozzle exit-substrate distance. Some useful information is also delivered on controlling the color and the composition of powders during their synthesis.

The present study deals with the investigation of electrically active damage induced by direct and through protecting oxide layer implantation of 11B+ ions. The residual defects have been determined by means of Deep Level Transient Spectroscopy (DLTS). It has been found that the number of defects is practically reduced to one centre when the implantation is performed through an oxide layer. The defect spectrum evolution, under the effect of the implant mass and the RTA treatments, has been also investigated. The defect generation kinetics, under annealing treatments, is found strongly depending on 11B+ ionic number reaching the substrate.

This paper presents a signal based approach to detect PWM inverter faults and motor unbalances in electrical drives. A diagnostic system which uses the control variables of the drive and the current measurements is presented. It is based on frequency analysis and on the energetic characterization of these variables in the PWM frequency domain. These method very simple to implement in real time have been successfully applied to an experimental system.

This paper deals with the study of shunt active filters used for suppressing particular harmonics generated by nonlinear loads in utility distribution power systems. Both structures of shunt active filter, voltage source active filter (VSAF) and current source active filter (CSAF), are considered. The analytical study of specific harmonics identification in a given spectrum is first presented. For simulation as well as experimentation the nonlinear load is a conventional three phase thyristor rectifier and harmonics 5 and 7 are selected to be eliminated by active filter. The whole system consisting of the ac power supply network, the SCR rectifier and the shunt active filter (VSAF/CSAF) is then simulated. The simulation results are discussed and the efficiency of the two kinds of active filter are compared. Finally, for the first structure, VSAF, the simulation results are confirmed by experimental test realized by means of a fully digital control active power filter developed in our laboratory.

Les algorithmes génétiques sont des méthodes adaptatives de plus en plus utilisée pour la résolution de certains problèmes d'optimisation. Le présent travail consiste d'une part, à mettre en œuvre un A.G sur des problèmes d'identification des machines électriques, et d'autre part à comparer ses performances avec les méthodes classiques tels que la méthode du maximum de vraisemblance et la méthode électrotechnique basée sur des essais à vides et en court-circuit. Ces méthodes sont appliquées sur des machines asynchrones de différentes puissances. Les résultats obtenus sont comparés selon certains critères, permettant de conclure sur la validité et la performance de chaque méthode.

The temperature profiles in wall-stabilized atmospheric pressure arcs in argon and Ar-CO2 mixture have been obtained at currents of 5 A to 40 A using spectroscopy techniques. The temperature profiles were measured using the absolute intensity of spectral lines. The monatomic excitation temperatures are determined experimentally from three chosen spectral lines of argon (415.86, 427.22, 696.54 nm), spectral lines of carbon (538.03, 477.175 nm) and spectral lines of triple oxygen (777.19, 777.42, 777.54 nm) in wall-stabilized arc. The results show the plasma had not the same composition locally as the gas injected in to the middle of the arc column. The results obtained are in good agreement with previously published data for pure argon and show the gradient formation of an arc core and the increase in axis temperature as the gas mixture is varied from pure argon to Ar-CO2 mixture. Another result of these investigations is to show the importance of high purity gas when using monatomic gases, the addition of even a few per cent of CO2 to argon having a drastic effect both upon extinction of the arc according to current values and upon the temperature profiles.

In RF cold plasma reactors, energy transfer from the generator to the discharge is not perfect and only 50 to 70 percent (or even less) of the power is effectively transmitted to the discharge, the reMayning part being mostly dissipated in the matching network. The choice of this circuit is therefore the most important factor in view to optimize the energy transfer from the power supply to the plasma. Two classical networks, Π- and L-type, are analytically studied in their interaction with the experimental device. From this study, in both cases, numerical values are deduced for the coil inductance, and a capacitance range is determined for the capacitors. An experimental study in argon plasma at pressure range of 40-200 mTorr and at 13.56 MHz, performed with the two types of matching networks leads to a much effective energy transfer with the L-type, which must be chosen in order to improve the energetic yield of surface processing (sputtering or etching for instance) with a RF plasma reactor.

Our work presents the study of bone remodeling scheme in the general case of n unit-elements model. The analytical result for the stationary states presented here as original was obtained and a condition which is necessary for the stability of the remodeling theory was derived. Forward finite-difference time-stepping is used to verify the prediction of the analytical study. This numerical study appears to confirm the analytical results.

L'objectif de cet article est de présenter la synthèse d'un modèle d'analyse pluridisciplinaire adapté à la caractérisation des performances d'un entraînement électrique alimenté à fréquence variable sous faible tension. Le modèle prend en compte le couplage entre les phénomènes électromagnétique, thermique et électrique. Il permet d'étudier le fonctionnement sous les conditions de régime thermique permanent ou transitoire qui interviennent dans la définition des cycles de travail des engins de traction à énergie embarquée. Ce modèle d'analyse constitue un élément d'une procédure de dimensionnement optimal qui sera développée dans un article séparé ; aussi l'exposé est-il conduit en explicitant les dépendances fonctionnelles entre les paramètres de dimensionnement et les performances. La procédure d'analyse est appliquée à l'étude d'un moteur à aimants permanents périphériques alimenté suivant le mode "brushless trapézoïdal" ; les performances sont évaluées pour deux types de cycle de travail : le cycle S1 en régime permanent, et le cycle S2 en régime thermique transitoire ; l'influence des paramètres de commande du convertisseur est examinée.

A personal computer driven equipment designed for Rayleigh scattering of Mössbauer radiation experiments at room temperature is described. The performances of the system were tested using like scatterers crystals with different mosaic divergences: lithium fluoride (LiF) and pyrolytic graphite (C). The equipment, suitable for any kind of Mössbauer scattering experiments, permits low and adjustable horizontal divergences of the incident beam.