Experimental study of electromagnetic disturbances in common and differential modes in a circuit based on two DC/DC boost static converter in parallel

Introduction. An electronic control and closing control at the switch (MOSFET) will allow a parallel connection of two DC/DC boost converters. The reason for paralleling converters is to increase the efficiency of the power conversion process. This means that the overall power loss on the main switches is half the power loss on the main switch of a converter. It has been proven that DC-DC converters operating in parallel have different dynamics than a single converter. In this paper, the study is based on a system of two boost converters operating in parallel under current mode control. Although two converters operating in parallel increase the efficiency of the system, if the control parameters are not chosen correctly, the system becomes unstable and starts to oscillate. Purpose of this work is to present the analysis of high frequency electromagnetic disturbances caused by the switching of power switches in DC/DC boost static converters mounted in parallel in the presence of cables. We will study the improvement of the electromagnetic compatibility performances which can be brought by the choice of a static converters for industrial use. Methods. For the study of the path of the currents in common mode and in differential mode, it was possible to evaluate experimentally the electromagnetic compatibility impact in common mode and in differential mode of two boost converters connected in parallel in an electric circuit in connection with the source through a printed circuit board of connection between the source and the load, while using the two basic methods, namely the prediction of the conducted electromagnetic interference, the temporal simulation and the frequency simulation. Results. All the obtained results are validated by experimental measurements carried out at the Djillali Liabes University Sidi-Bel-Abbes in Laboratory of Applications of Plasma, Electrostatics and Electromagnetic Compatibility (APELEC). The experimental results obtained in common mode and in differential mode at low, medium and high frequencies are compared between the parallel boost test with and without electromagnetic compatibility filter

Face detection using classifiers cascade based on vector angle measure and multi-modal representation

This paper deals with face detection in still gray level images which is the first step in many automatic systems like video surveillance, face recognition, and images data base management. We propose a new face detection method using a classifiers cascade, each of which is based on a vector angle similarity measure between the investigated window and the face and nonface representatives (centroids). The latter are obtained using a clustering algorithm based on the same measure within the current training data sets, namely the low confidence classified samples at the previous stage of the cascade. First experiment results on refereed face data test sets are very satisfactory

Gas heating in fast pulsed discharges in N

The dynamics of gas heating in fast pulsed discharges in nitrogen-oxygen mixtures was analyzed using a state-specific plasmachemical model and an energy conservation equation. It was shown that the heating rate changes over time according to the changes of the species involved in the heating processes. An increasing dependence on time was shown. The results show that higher electron density, electric field or partial pressure of oxygen leads to a faster gas heating. However, the heating rate associated with excitation of vibrational and electronic degrees of freedom is almost independent of the value of the applied field in the studied range of fields

Drift invariant gas recognition technique for on chip tin oxide gas sensor array

The purpose of this paper is the study of the robustness of a new low complexity recognition method based on the measurement issued from an on chip 4 x 4 Tin oxide gas sensor array. The recognition system is based on a vector angle similarity measure between the query gas and the representatives of the different gas classes. The latter are obtained using a clustering algorithm based on the same measure within the training data set. Experimented results show more than 98% of good recognition and the robustness or the proposed approach is tested by recognizing gas measurements with simulated drift. Less than 1% of performance degradation is noted at the worst case

Temperature modulation for tin-oxide gas sensors

This paper presents a study of temperature modulation for tin-oxide gas sensor. The main objective of this work is to per-form temperature modulation experimental setup for tin oxide gas sensors in order to improve the selectivity of the sensor array and to virtually increase the number of sensors. Typically, tin oxide sensors operate by heating at a relatively high temperature (around 300 degrees C a microhotplate structure). A convex microhotplate is proposed in order to improve the thermal properties of the structure and enable efficient temperature modulation process to be carried-out. Temperature modulation is shown to increase the number of our sensors from 16 physical sensors (integrated on-chip) up to 12 000 virtual sensors. This will enable the emulation of a very large number of sensors typically found in biological systems

Probabilistic satellite image fusion

Remote sensing satellite images play an important role in many applications such as environment and agriculture lands monitoring. In such images the scene is usually observed with different modalities, e.g. wavelengths. Image Fusion is an important analysis tool that summarizes the available information in a unique composite image. This paper proposes a new transform domain image fusion (IF) algorithm based on a hierarchical vector hidden Markov model (HHMM) and the mixture of probabilistic principal component analysers. Results on real Landsat images, quantified subjectively and using objective measures, are very satisfactory. © 2009 Springer Berlin Heidelberg

Role of the excited electronic states in the ionization of ambient air by a nanosecond discharge

International audienceIn this paper, the mechanism of air ionization by a single nanosecond discharge under atmospheric conditions is studied by numerical simulations. The plasma kinetics is solved with ZDPlasKin and the electron energy distribution function is calculated with BOLSIG+. The originality of the model is to consider not only the excited electronic states of N2, but also the excited electronic states of O and N. These states are shown to have a primary importance in the ionization of the plasma for ne > 10 17 cm-3. It is shown that a non-equilibrium plasma (Te > Tgas) at ne = 10 17 cm-3 can reach full ionization and thermalization (Te = Tgas ≈ 3 eV, ne ≈ 10 19 cm-3) in less than half a nanosecond under a field usually encountered in nanosecond discharges