The aim of this paper is to present a method of detection and isolation of intermittent misfiring in power switches of a three phase inverter feeding an induction machine drive. The detection and diagnosis procedure is based solely on the output currents of the inverter flowing into the machine windings. The measured currents are transformed in the two dimensional frame obtained with the Concordia transform. The data are then treated by a time-average method. The results even promising lack of accuracy mainly in the fault isolation step. To enhance the fault detection and diagnosis by the use of the information enclosed in the data, a Principal Component Analysis classifier is applied. The detection of a fault occurrence is made by a two-class classifier. The isolation is a two-step approach which uses the Linear Discriminant Analysis; the first is to identify the faulty leg with a three-class classifier and the second one discriminates the faulty power switch. Both methods are evaluated with experimental data and pattern recognition method proves its effectiveness and accuracy in the faulty leg detection and isolation.

Electrostatic filtration is a process that has been studied for more than a century. One of the most recent applications is Diesel exhaust gas aftertreatment. More specifically, car manufacturers are very interested in using electrical discharge phenomena to remove the soot particles from exhaust gases. This process could be a feasible alternative to the Diesel particulate filter used at the present time. The aim of this paper is to investigate the effects of repetitive voltage impulses on the treatment efficiency on soot particles and to compare results with those achieved when a DC supply is used. The study was divided into two steps: in the first, a study of the modes of discharge which develop in an electrostatic precipitator allows us to optimize both the geometry of an ESP and a hybrid pulsed power/direct voltage supply. This study was performed without gas flow. In the second step, investigations concerning treatment efficiency were carried out under practical conditions using an engine test bench. Results show that the combination of direct voltage (–7 kV) and pulsed voltage (–14 kV, 3 kHz) provides treatment efficiency close to 75% using electrical power three times lower than that required using a DC supply.

The rapid expansion of supercritical solution (RESS) is a promising process for the production of small particles with a narrow size distribution. It involves an expansion of a supercritical solution through a small nozzle to generate a rapid nucleation and then the formation of ultrafine particles. The particles are transported by a powerful jet developed in the expansion chamber. The particle size distribution (PSD) of the obtained fine powders depends on the hydrodynamic conditions in the pre- and post-expansion unit, the nature of solute-solvent system, as well as on the nozzle geometry, and diameter. In this work, we have developed a numerical simulation of both transport and Brownian coagulation of spherical particles in the expansion chamber by resolving the general dynamic equation (GDE). This simulation has permitted to control the temporal evolution of PSD characterizing each class of particles. These PSD field evolutions show that the particles of each class get round the Mach disk taking refuge on the jet boundaries where the Brownian coagulation is more pronounced. Therefore, these particles whose size depends on thermodynamic and geometrical conditions are deposited on the flat plate as a ring. We notice that the narrowest distribution function of the deposited particles on the flat plate is obtained for the largest nozzle orifice diameters and the lowest expansion pressure.

To support experimental investigations, a model based on ChemkinTM software was used to simulate gas phase and surface chemistry during plasma-enhanced catalytic CVD of carbon nanotubes. According to these calculations, gas phase composition, etching process and growth rates are calculated. The role of several carbon species, hydrocarbon molecules and ions in the growth mechanism of carbon nanotubes is presented in this study. Study of different conditions of gas phase activation sources and pressure is performed.

Composition of the applied shielding gas has a strong influence on physical properties of the plasma and parameters of the welding process. In particular, increase of the percentage of carbon dioxide in argon results in an increase of the transition current value while changing from the globular to spray mode of metal transfer during the welding process. In order to explain this phenomenon, the MIG/MAG welding arc plasma was investigated for different mixtures of argon and carbon dioxide in the shielding gas. Applying a fast camera, recording distribution of spectral lines of the plasma components, we noticed some phenomena not described yet in the literature. Especially, there is a limit in the percentage of relative concentration CO2/Ar beyond which the arc shape is significantly modified.

This paper describes implementation and initial evaluation of variable friction displays. We first analyse a device that comprises a stator of an ultrasonic motor supplied by only one channel. In this way, the stator does not induce any rotative movement but creates a slippery feeling on the stator's surface. Considering the range of frequency and amplitude needed to obtain this phenomenon, we interpret it as the squeeze film effect, which may be the dominant factor causing an impression of lubrication. This effect is thus able to decrease the friction coefficient between the fingertip and the stator as a function of the vibration amplitude. Moreover, if we add a position sensor, we can create a textured surface by generating alternatively sliding and braking sensations by tuning the vibration amplitude of the wave. Then, based on the principle of the first device, another device is proposed in order to enable a free exploration of the surface, according to ergonomic requirements.

We report on the production of composite semiconductor CdZnS nanoparticles by adopting an inverse micellar route, using bis (2-ethylhexyl) sulfosuccinate (aerosol-AOT) as surfactant and with a degree of hydration w0 = [ H2O] : [AOT] = 8.9. Prior to bioconjugation (conjugation with bovine serum albumin (BSA)), the hydrophobic surface of the nanocrystals were made hydrophilic with thiol treatment (reacting with mercapto acetic acid). We compare photophysical nature of as prepared, thio-stabilized and bioconjugated CdZnS nanoparticles using absorption/emission spectroscopy and ultrafast photoluminescence decay measurements. The change-over from nonzero anisotropy (untreated) to zero anisotropy (bioconjugated) is assigned to the depolarized emission due to the surface reconstruction owing to BSA adsorption into the surface vacancies. Exploration of the dynamics of photophysical features would be promising for biomolecular sensing, labeling, and imaging applications.

The influence of adsorbed oxygen at the first interface of single-crystal Fe(001)/MgO(001)/Fe(001) magnetic tunnel junctions is investigated. Firstly, the adsorption kinetics of O2 on the Fe(001) surface is studied in the monolayer regime by X-ray photoelectrons spectroscopy and scanning tunnelling microscopy experiments. We show that different species exist at the oxidized surface. The tunnel magneto-resistance of oxygen-doped magnetic tunnel junctions is found to decrease but remains large even for oxygen coverages exceeding one monolayer.

Zirconium oxide thin films were deposited by sputtering a ZrO2 target under an argon-oxygen gas mixture and different total gas pressures. Their composition, structure and optical constants were characterised by mean of Auger profiles, XRD, XPS, m-line and UV-visible spectroscopies. All the deposits were found to be sub-stoechiometric with O/Zr ratio decreasing from 1.6 to 1.45 when the deposition pressure increased from 0.01 to 0.05 Torr. A SRIM simulation was used to explain this behaviour. The XRD showed a monoclinic phase for all sample with different grain size and residual stress. Finally, the optical constants were determined. The refractive index decreased slightly when the deposition pressure increased whereas the optical gap and the Urbach energy were found to be quite constant whatever the sputtering pressure.