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Boussaada I.,University Paris - Sud | Boussaada I.,Polytechnic Institute of Advanced Science
Journal of Computational and Nonlinear Dynamics | Year: 2012

The problem of local linearizability of the planar linear center perturbed by cubic non- linearities in all generalities on the system parameters (14 parameters) is far from being solved. The synchronization problem (as noted in Pikovsky, A., Rosenblum, M., and Kurths, J., 2003, Synchronization: A Universal Concept in Nonlinear Sciences, Cambridge Nonlinear Science Series, Cambridge University Press, UK, and Blekhman, I. I., 1988, Synchronisation in Science and Technology, ASME Press Translations, New York) consists in bringing appropriate modifications on a given system to obtain a desired dynamic. The desired phase portrait along this paper contains a compact region around a singular point at the origin in which lie periodic orbits with the same period (independently from the chosen initial conditions). In this paper, starting from a five parameters non isochronous Chouikha cubic system (Chouikha, A. R., 2007, Isochronous Centers of Lienard Type Equations and Applications, J. Math. Anal. Appl., 331, pp. 358-376) we identify all possible monomial perturbations of degree d {2, 3} insuring local linearizability of the perturbed system. The necessary conditions are obtained by the Normal Forms method. These conditions are real algebraic equations (multivariate polynomials) in the parameters of the studied ordinary differential system. The efficient algorithm FGb (J. C. Faugre, FGb Salsa Software, http://fgbrs.lip6.fr) for computing the Gröbner basis is used. For the family studied in this paper, an exhaustive list of possible parameters values insuring local linearizability is established. All the found cases are already known in the literature but the contexts are different since our object is the synchronisation rather than the classification. This paper can be seen as a direct continuation of several new works concerned with the hinting of cubic isochronous centers, (in particular Bardet, M., and Boussaada, I., 2011, Compexity Reduction of C-algorithm, App. Math. Comp., in press; Boussaada, I., Chouikha, A. R., and Strelcyn, J.-M., 2011, Isochronicity Conditions for some Planar Polynomial Systems, Bull. Sci. Math, 135(1), pp. 89-112; Bardet, M., Boussaada, I., Chouikha, A. R., and Strelcyn, J.-M., 2011, Isochronicity Conditions for some Planar Polynomial Systems, Bull. Sci. Math, 135(2), pp. 230-249; and furthermore, it can be considered as an adaptation of a qualitative theory method to a synchronization problem. © 2012 American Society of Mechanical Engineers.

Benabid S.,Polytechnic Institute of Advanced Science | Aghdam E.N.,Sahand University of Technology
International Conference on Applied Electronics | Year: 2015

A 6th order bandpass continuous-time sigma delta modulator centered at 300MHz suitable for Software Defined Radio receiver is presented. This modulator is implemented in a standard low-cost 0.35μm CMOS technology. Several Q-enhanced LC resonators are implemented in a parallel structure using highly linear operational transconductance amplifiers (OTA), LC tank, and transconductor acts as a negative resistance to compensate the ohmic losses in inductor. Furthermore, an improved method employing two 3-bit flash ADC as a loop quantizer allows to double the sampling frequency and to relax the comparator requirements. Consequently we can design a modulator clocked at 1.2GHz allowing the integration of passive LC-filters in this standard technology. Transistor level simulations show that the modulator achieves a signal-to-noise and distortion-ratio (SNDR) of 82.6dB over a 6MHz signal band. © 2014 University of West Bohemia.

Coimbra S.,Polytechnic Institute of Advanced Science | Coimbra S.,University of Porto | Figueiredo A.,University of Coimbra | Santos-Silva A.,University of Porto
Core Evidence | Year: 2014

Advances in knowledge regarding the pathogenesis of psoriasis have allowed the development of a new class of agents known as biologic drugs. Data confirm that T helper (Th)17 and interleukin (IL)-17 signaling has a crucial role in the pathogenesis of the disease. High levels of IL-17 and Th17-related cytokines have been reported in psoriasis, leading to the suggestion of agents targeting IL-17 as a potential therapeutic strategy in psoriasis. Brodalumab is a human monoclonal antibody that targets IL-17 receptor A, blocking the effects of IL-17A, IL-17F, and IL-17E. Data from Phase I and Phase II clinical trials indicate that brodalumab has a favorable safety and tolerability profile, with strong clinical activity, suggesting that it is a potential tool for use in the treatment of moderate-to-severe psoriasis. © 2014 Coimbra et al.

Beauvalet L.,University Pierre and Marie Curie | Robert V.,University Pierre and Marie Curie | Robert V.,Polytechnic Institute of Advanced Science | Lainey V.,University Pierre and Marie Curie | And 2 more authors.
Astronomy and Astrophysics | Year: 2013

Because of Pluto's distance from the Sun, the Pluto system has not yet completed a revolution since its discovery, hence an uncertain heliocentric distance. In this paper, we present the fitting of our dynamical model ODIN (Orbite, Dynamique et Intégration Numérique) to observations. The small satellites P4 and P5 are not taken into account. We fitted our model to the measured absolute coordinates (RA, DEC) of Pluto, and to the measured positions of the satellites relative to Pluto. The masses we found for the bodies of the system are consistent with those of previous studies. Yet the masses of the small satellites Nix and Hydra are artificially constrained by the number of observations of Charon. The best way to improve the determination of their masses would be to use observations of P4 and P5, but there are still not enough published observations. Concerning the heliocentric distance of the system, we compared the value we obtained using ODIN and those of other models. The difference between the models far exceeds the uncertainty needed (about 1000 km) for the mission New Horizons. A new astrometric reduction of old photographic plates may be an efficient way to constrain this distance. The ephemeris for Pluto's satellites is available on the web page of the IMCCE at http://www.imcce.fr/hosted-sites/saimirror/nssreq9hf.htm. The complete version of the ephemeris is available as a SPICE kernel at http://www.imcce.fr/ beauvalet/. © 2013 ESO.

Escareno J.-A.,Polytechnic Institute of Advanced Science | Rakotondrabe M.,University of Franche Comte | Habineza D.,University of Franche Comte
Control Engineering Practice | Year: 2015

This paper deals with the control of a two degrees of freedom (2-DOF) piezoelectric actuator for precise positioning and which exhibits strong hysteresis nonlinearity and strong cross-couplings. To tackle the nonlinearity and the cross-couplings, we propose two decoupled models in which they are considered as (fictive) external disturbances which require proper characterization. Then, a backstepping technique is proposed to construct a robust controller that merges sliding-mode and adaptive schemes. Extensive experimental tests are finally carried out to prove the efficiency of the modeling and control technique proposed. © 2015 Elsevier Ltd.

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