This paper presents a method for detecting faults in the induction machine using a flux sensor which measures the external radial leakage magnetic field of the machine. The procedure uses the spectral lines that correspond to the slotting effect which causes harmonics in the machine air gap. These harmonic frequencies, which are about a few kHz occur in a part of the spectra which is not very dense compared to the one that corresponds to the low frequencies due to the supply or the rotor revolution speed. The considered components can also be detected in the radial magnetic field flowing out of the machine. It can be shown that specific faults lead to additional spectral lines which appear clearly near the original ones due to the slotting effect. Two faults, which can be detected with the same magnetic flux sensor, are presented in this paper: the first one corresponds to a broken rotor bar, the second one is a stator inter turn short circuit.

Following the total yield approach (used to predict the sign of charging of electron irradiated insulators) a positive charging is expected when the primary beam energy E p issituated in the energy range where the number of outgoing electrons, $(\delta + \eta) I_0$ , is largerthan the number of incoming electrons, I 0. But a negative charging is often experimentally observedwhen a positive charging is predicted. The present paper is an attempt to elucidate this experimentalfact. The arguments being developed are based on the use of a dynamic double layer model (+ for the secondary electron mission, SEE; − for the incident electron implantation) which explains a negative charging via the influence of an evolving S-shape potential function,V(z), which induces a partial freezing of the nominal (uncharged) SEE, δ°, combined to a progressive compression of the negative space charge below the surface. Theobserved large difference in the measurements of the yield by using pulse excitationmethods, or by permanent irradiation methods, δ° or δ is then explained.Furthermore, the influence of an oblique incidence is also deduced.

In point-to-plane corona discharges in air, the collisions of charged particles with neutral particles induce a gas movement between the point to the plane called electric wind. A one-dimensional model of the neutral particle velocity along the discharge axis and between the electrodes is first developed. Laser Doppler Anemometry is used to measure the axial velocity profile of the gas between the electrodes. Discrepancies between experimental results and predictions of the on-axis velocity are discussed. Finally, the measured velocity profile compares quite well with a cos5 θ distribution. Significant differences between measured and cos5 θ profiles are observed near the discharge axis which could be attributed to the presence of seeding particles.  

Two different atmospheric pressure microplasma systems are discussed and used for the synthesis and surface engineering of a range of nanomaterials. Specifically a gas-phase approach from vaporized tetramethylsilane has been used to synthesize silicon carbide nanoparticles with diameters below 10 nm. A different microplasma system that interfaces with a liquid solution has then been used for the synthesis of surfactant-free electrically stabilized gold nanoparticles with varying size. A similar microplasma-liquid system has been finally successfully used to tailor surface properties of silicon nanoparticles and to reduce graphene oxide into graphene. The synthesis and surface engineering mechanisms are also discussed.

This paper describes implementation and initial evaluation ofvariable friction displays. We first analyse a device that comprises a stator of an ultrasonic motor supplied by onlyone channel. In this way, the stator does not induce any rotative movement butcreates a slippery feeling on the stator's surface. Considering the range of frequency and amplitude needed to obtain this phenomenon, weinterpret it as the squeeze film effect, which may be the dominant factor causing an impression of lubrication. This effect is thus able to decreasethe 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 isproposed in order to enable a free exploration of the surface, according to ergonomic requirements.

The aim of this work is to identify the main process responsible for sterilization of Geobacillus Stearothermophilus spores in O2:N2 RF inductively coupled plasma. In order to meet this objective the sterilization efficiencies of discharges in mixtures differing in the initial O2/N2 ratios are compared with plasma properties and with scanning electron microscopy images of treated spores. According to the obtained results it can be concluded that under our experimental conditions the time needed to reach complete sterilization is more related to O atom density than UV radiation intensity, i.e. complete sterilization is not related only to DNA damage as in UV sterilization but more likely to the etching of the spore.

This paper presents a dynamical non linear model of the spatial time-dependant evolution of A3 point during a particular sequence of resistance spot welding in steel material. The model is based on a solution to the heat equation, expressed in cylindrical coordinates inside the joint area, and when the source term is attributed to the electrical power. By the mean of the steel binary Fe–C diagram and the deduced t-dependant temperature rise profile, an estimation of the A3 point spatial range date is given and compared to further results. The obtained temperature profile is yielded, taking into account main parameters variations, as a guide to non-destructive protocols and thermal characteristics investigation

Shock wave generation from laser-produced plasma in water confinement regime for an incident 25–30 ns / 40 J / λ = 1.064 µm laser beam has been studied. Transmitivity measurement of the parasitic plasma breakdown at the surface of water confinement has been performed with a continuous laser probe. Above 6 GW/cm2 incident laser intensity, the critical electronic density for the laser wavelength is achieved inside the plasma by cascade ionization during the pulse duration. Above 10 GW/cm2, peak power density transmitted through the plasma saturates. The laser pulse transmitted through the breakdown plasma corresponds to the part of incident laser pulse preceding the transmission cut-off.

The use of CR-39, a solid state nuclear track detector, to detect the emission of energetic charged particles during Pd/D co-deposition is demonstrated. The pits observed in the CR-39 are attributed to the Pd/D cathode and are not due to radionuclide contamination in the cell components; nor to the impingement of D2 bubbles on the surface of the CR-39; nor to chemical attack by D2, O2, or Cl2. The features (i.e., optical contrast, shape, and bright spot in the center of the pit) of the pits generated during Pd/D co-deposition are consistent with those observed for pits that are of a nuclear origin.

High resolution neutron diffraction patterns of BaCex Zr1−x O3 (x = 0, 0.1, 0.4,0.8) were obtained at various temperatures. The phase diagram that was deduced from Raman measurements has been confirmed. Structural transitions occur in a fixed order Pnma-Imma- R $\bar{3}$ c-Pm3m as a function of temperature or composition. For BaCeO3, the large volume change that has been previously claimed at the Imma-R $\bar{3}$ c transition has been revisited and found inconsistent. For a given composition, the cell volume increases when temperature increases, but the MO6 (M=Ce-Zr) octahedron volume decreases. It is shown that the ratio of the cell volume to the octahedron volume is a good indicator of the phase transitions. Transitions occur at fixed values (5.77, 5.80 and 6 for the Pnma-Imma, Imma-R $\bar{3}$ c and R $\bar{3}$ c-Pm3m transitions respectively) independently of composition.

In this work, we present various examples of assistance to the restoration of works of art by stimulated infrared thermography. We show initially that the method allows the detection of delamination located in mural paintings, such as in the “Saint Christophe” of the Campana collection of the Louvre French museum. We show then that it also makes it possible to detect delaminations or galleries of worms in marquetries. We show in a third stage that it provides for the detection of detachment of grayness in stained glasses. We show in a fourth stage that it allows the visualization of shards or metal inserts located in a Greek “panathénaque” amphora of the French National museum of the Ceramics of Sevres. We show finally, that the method permits the detection of a crack located in an ovoid vase of the same French National museum of the Ceramics of Sevres.

A new approach to determine the displacement field between areference and a deformed image is introduced. The method is based on aspectral decomposition of the displacement field which is determinedthrough a multi-scale approach. The method is tested here on anartificial example by using computer-generated images devoid of boundaryeffects (i.e., periodic boundary conditions are used in the image texture anddisplacement field). The performance of the proposed algorithm allowsfor the determination of the prescribed displacement field up to machineprecision, for a strain field whose trace extends from −50% to 40%with a root-mean-square average of 15%, within sub-minute runs on astandard PC.

We reported material characterization of the nano-structured TiO2 thin films prepared by the sol-gel dip-coating process on glass substrates. The dependence of the structural, morphological and optical properties of the synthesized films on the fabrication parameters such as withdrawal velocity and annealing temperature were investigated by the techniques of X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-visible spectrophotometry. The results indicate that for the TiO2 films annealed at 500 °C there exhibits (1 0 1) XRD peak corresponding to the anatase phase of TiO2. The latter is consistent with the recorded Raman signal observed at 142 cm-1 (Eg mode) and 391 cm-1 (B1g mode), respectively. From the analyses made on the SEM micrographs and AFM images, it was revealed that the morphology and surface roughness of the thin films would depend on the withdrawal speed and the heat treatment temperature. The UV-visible spectroscopy analyses show that all the films were transparent in the visible region with an average transmittance of more than 70%. With an increase on the dip-coating speed from 1 cm/min to 3 cm/min, we observed a spectral red shift of the absorption edge from 3.76 eV to 3.71 eV, indicating a decrease in the bandgap energy (Eg) of the films.

Nano-imprint lithography (NIL) is one of the most promising patterning technologies, in which nano- and micro-patterns are fabricated on various substrates. NIL provides high throughput and low cost in fabricating nano-structures due to its simple process and allows resolution below 10 nm without issues of light diffraction with conventional lithographic techniques. Its patterning mechanism is based on mechanical deformation of a polymer resist, which is simply done by pressing with a mold. This patterning mechanism also enables inorganic and organic-inorganic hybrid materials to be directly patterned by NIL. This article covers the recent progress of NIL-based direct patterning techniques and their applications to devices. Recently, functional nano- and micro-patterns have been applied to various electronic devices for the enhancement of overall performance. Fabrication methods of these devices are difficult using convention lithographic techniques due to complex processes, high cost and low throughput. Direct NIL technique using functional resist can simply fabricate functional nano- and micro-structures and thus can be usefully applied to various industries.

Optical Emission Spectroscopy (OES) is used to investigate the effect of argon gas mixing on the electron temperature, the degree of nitrogen dissociation and the active species concentration in a 13.56 MHz radio frequency (RF) sustained nitrogen plasma. The electron temperature is determined from Ar-I emission line intensities by using the modified Boltzmann's plot method and is found to be increased with argon mixing in nitrogen plasma. The concentration of active species $\rm N_2(C ^3\Pi_{\it u})$ and $\rm N_2^+ (B ^2\Sigma_{\it u}^+)$ is monitored in terms of the emission intensities of nitrogen (0–0) bands of the second positive and the first negative systems respectively. The concentration of $\rm N_2 (C^3\Pi_{\it u})$ active species along with the degree of N2-dissociation is appreciably enhanced by argon mixing signifying the role of argon metastables in the excitation and dissociation processes.

Dielectric barrier discharges (DBD) in air at atmospheric pressure and at low frequency are mainly constituted of thin transient plasma filaments (or microdischarges) with radii of a few hundreds of micrometers. In this work, we consider a point-to-plane geometry with the dielectric covering the plane electrode. Plasma filaments are initiated by streamers, starting from the high-field region close to the point electrode. The plasma filaments deposit charges on the dielectric plate which screen the electric field and lead to an extinction of the discharge filaments. In this work we experimentally demonstrate the synchronous start of several filaments in a time range of less than a few tens of nanoseconds and we show that the charges deposited on the dielectric have a strong impact on the discharge structure. This is validated using a simple electrostatic model. Then, the dynamics of the 2D streamer propagation in the gas gap and its interaction with the dielectric plane is calculated. The influence of space charges and surface charges on the discharge structure are discussed and compared with the experiment.

The time dependence of the surface potential of an insulating materialis theoretically investigated in the case of simultaneous surface and volume ohmicconduction. When the material presents a constant surface conductivity, the first partof the decrease with time of the surface potential is strongly influenced by theinitial distribution of charges and cannot be used to determine the surfaceconductivity. On the other hand, at rather long times after the surface has beencharged, the potential of the surface follows an exponential variation with time, the expression of the corresponding time constant is given in different cases. This modelis found in good agreement with experiments performed with photo-oxidized epoxy resinsplaced in a humid atmosphere.

We measured the single-photon detection efficiency of NbN superconducting single-photon detectors as a function of the polarization state of the incident light for different wavelengths in the range from 488 nm to 1550 nm. The polarization contrast varies from ~5% at 488 nm to ~30% at 1550 nm, in good agreement with numerical calculations. We use an optical-impedance model to describe the absorption for polarization parallel to the wires of the detector. For the extremely lossy NbN material, the absorption can be kept constant by keeping the product of layer thickness and filling factor constant. As a consequence, the maximum possible absorption is independent of filling factor. By illuminating the detector through the substrate, an absorption efficiency of ~70% can be reached for a detector on Si or GaAs, without the need for an optical cavity.

The rapid development of low-power consumption electronics and the possibility of harvesting energy from environmental sources can make totally autonomous wireless devices. Using piezoelectric materials to convert the mechanical energy into electrical energy for batteries of wireless devices in order to extend the lifetime is the focus in many researches in the recent years. It is important and efficient to improve the energy harvesting by designing an optimal interface between piezoelectric device and the load. In this paper, a self-powered piezoelectric energy harvesting device is proposed based on the velocity control synchronized switching harvesting on inductor technique (V–SSHI). Comparing to the standard full bridge rectifier technique, the synchronized switching harvesting on inductor (SSHI) technique can highly improve harvesting efficiency. However, in real applications when the energy harvesting device is associated with wireless sensor network (WSN), the SSHI technique needs to be implemented and requires being self-powered. The conventional technique to implement self-powered SSHI is to use bipolar transistors as voltage peak detector. In this paper, a new self-powered device is proposed, using velocity control to switch the MOSFET more accurately than in the conventional technique. The concept of design and the theoretical analysis are presented in detail. Experimental results are examined.

This paper addresses a multiscale strategy for the prediction of anhysteretic magneto-elastic behavior and its application to the definition of a magneto-elastic constitutive law for Terfenol-D. The multiscale modeling is based on an energetic procedure at the single crystal scale. Localization and homogenization procedures are then applied to deduce the constitutive law of polycrystalline media from the behavior of the corresponding single crystal. The method is applied first to define the magneto-elastic behavior of single crystals, and the application to polycrystalline samples is then considered. Modeling results are compared to experimental data.