Experimental nonlinear torque control of a permanent-magnetsynchronous motor using saliency

In this paper, a new nonlinear control strategy is proposed for a permanent-magnet salient-pole synchronous motor. This control strategy simultaneously achieves accurate torque control and copper losses minimization without recurring to an internal current loop nor to any feedforward compensation. It takes advantage of the rotor saliency by allowing the current (i_d) to have nonzero values. This, in turn, allows us to increase the power factor of the machine and to raise the maximum admissible torque. We apply input-output linearization techniques where the inputs are the stator voltages and the outputs are the torque and a judiciously chosen new output. This new output insures a well-defined relative degree and is linked to the copper losses in such a way that, when forced to zero, it leads to maximum machine efficiency. The performance of our nonlinear controller is demonstrated by a real-time implementation using a digital signal processor (DSP) chip on a permanent-magnet salient-pole synchronous motor with sinusoidal flux distribution. The results are compared to the ones obtained with a scheme which forces the i_d current to zero     

AeDEn: An adaptive framework for dynamic distribution over mobile environments

Mobile computing is a domain in great expansion. Wireless networks (gsm, satellite, etc) and Portable Information Appliances pias (laptops, PDAs, cellular phones, etc) are developing very rapidly. More and more mobile users would like to execute their applications with the same quality of service as on their desktop station, whatever their needs in memory and computing power. Using such applications in a mobile environment raises new challenges. Some of these applications are extremely costly in system and network resources, whereas pias resources are poor and wireless networks offer a very variable quality of connection. In this paper we propose an adaptive and dynamic distribution of applications on the local environment to overcome the poorness of available resources on pias, and to reduce and regulate variability effects. Moreover, due to the variety of distribution policies, we propose a framework providing adaptive distribution policies.     

Frame transfer CCDs for digital still cameras: concept, design, andevaluation

Digital still cameras are becoming a widely used alternative for conventional silver-halide cameras. This paper presents first the concept of frame-transfer CCD imagers designed for consumer digital cameras. Next, the different modes of operation are explained in detail and compared with alternative approaches. Finally, extensive evaluation results on four different imagers using this new concept are presented. It will be demonstrated that the flexible modes of operation, the high dynamic range, and excellent optical properties of FT-CCDs make them very suited for this type of electronic imaging     

Time reversal terahertz imaging

We describe a technique for imaging in the terahertz regime using time reversal of single-cycle pulses. Specifically, the time-reversal symmetry of Maxwell's wave equation is exploited to reconstruct the transmission function of a diffracting aperture by inverting the diffracted fields. After deriving a time-reversed form of the Huygens-Fresnel diffraction integral, we demonstrate through simulation and experiment the reconstruction of one-dimensional and two-dimensional (2-D) objects. A means to obtain data efficiently for reconstruction of 2-D apertures is described. The spatial resolution determined by the Sparrow criterion is found to correspond to approximately 30% of the peak wavelength and 85% of the mean wavelength of the power spectrum of the single-cycle waveform. Finally, the modulation transfer function for the imaging method is simulated and is shown to be nearly diffraction-limited when compared to an ideal imaging system.     

Two-electrode DFB laser filter used as a wide tunable narrow-bandFM receiver: tuning analysis, characteristics and experimental FSK-WDMsystem

Characteristics of a two-electrode DFB laser filter are studied both theoretically and experimentally. Using a matrix analysis of spontaneous emission, a continuous tuning range of 6.7 Å is achieved by changing both net field gains of the two electrodes. A total discontinuous tuning range of over 10 nm comprising alternating mode jumps and continuous tuning range of 4 Å are measured experimentally. The laser filter presents a FWHM bandwidth of 5 GHz which depends on the optical input power. In addition, it is demonstrated that a DFB laser filter can act as a frequency discriminator/photodetector, i.e., a narrow-band FM receiver, with a uniform bandwidth of 1.5 GHz. Using the two-electrode DFB laser for both transmitter and receiver, a two-channel FSK-WDM transmission system utilizing the discontinuous tuning range is reported. The advantage of such a device is the simplicity as compared to the heterodyne technique     

Programming real-time applications with SIGNAL

The authors present the main features of the SIGNAL language and its compiler. Designed to provide safe real time system programming, the SIGNAL language is based on synchronous principles. Its semantics are defined via a mathematical model of multiple-clocked flows of data and events. SIGNAL programs describe relations on such objects, so that it is possible to program a real time application via constraints. The compiler calculates the solutions of the system and thus can be used as a proof system. The equational approach is a natural way to derive multiprocessor executions of a program. This approach uses a graphical interface of a block-diagram style, and the system is illustrated on a speech recognition application     

Adhesion to and invasion of HeLa cells by pathogenic Escherichia coli carrying the afa-3 gene cluster are mediated by the AfaE and AfaD proteins, respectively

The afa-3 gene cluster, expressed by uropathogenic and diarrhea-associated Escherichia coli strains, determines the formation of an afimbrial adhesive sheath composed of the AfaD and AfaE-III adhesins. The adherence to HeLa cells by recombinant HB101 strains producing both or only one of these two adhesins was investigated. Ultrastructural analyses of the interaction and gentamicin protection assays showed adherence to HeLa cells by HB101 producing both the AfaD and AfaE-III proteins and internalization of a subpopulation of the bacteria into the cells. The interactions of HeLa cells either with HB101 mutants producing AfaD or AfaE-III or with polystyrene beads coated with purified His6-tagged AfaD or His6-tagged AfaE-III proteins were studied. These experiments demonstrated that AfaE-III allows binding to HeLa cells and that AfaD mediates the internalization of the adherent bacteria. Ultrastructural analyses of the interaction of His6-AfaD-gold complexes with HeLa cells confirmed that AfaD is able to bind to the HeLa cell surface and indicated that it penetrates the cells via clathrin vesicles. These data demonstrate that the afa gene cluster is unique among bacteria, as alone it encodes both adhesion to and invasion of epithelial cells.     

Estimation of the distribution of the maximum theoretical intake for ten additives in France.

Three European directives imply for all member states an evaluation of food additives intakes. This paper describes the French approach, using a step-by-step procedure to evaluate, at a national level, the consumption of 10 food additives or groups of additives (E100, curcumin; E160b, annatto; E200-203, sorbic acid and salts; E210-213, benzoic acid and salts; E220-224, 226-228, sulphites; E249-250, nitrites; E297, fumaric acid; E473-474, sucrose esters and sucroglycerides; E491-492, stearoyl lactates; E952, cyclamic acid). The results are reassuring for the general population, except for sulphites.