Nonlinear Control Strategies of an Autonomous Double Fed Induction Generator Based Wind Energy Conversion Systems

In the last few decades, among the wide range of renewable energy sources, wind energy is widely used. Variable speed wind energy conversion systems based on double fed induction generator have a considerable interest mostly in case of islanded networks and/or isolated applications. In this paper, as a means to supply remote areas, an investigation of a wind energy conversion system (WECS) based on a double fed induction generator (DFIG) is carried out. The presence of both wind turbine aerodynamics and DFIG coupled dynamics causes strong nonlinearities in the studied system. Wind speed and demanded power variations have a major impact on the quality of the produced energy. In order to control and maintain the stator output voltage and frequency at their nominal values (220 V/50 Hz) under wind speed and load variations, this work presents a study of three kinds of controllers: PI, Back-Stepping and Sliding Mode controllers. These controllers are integrated in the studied system and a comparison of their dynamic performances has been developed. Moreover, in order to ensure the rotor side converter safety on the one hand and to guarantee an optimal operation of the DFIG on the other hand, a management strategy is proposed in this work. Simulation results are performed using Matlab/Simulink environment and show the effectiveness and the accuracy of each controller compared to others mainly with the presence of wind speed and load demand variations

Methicillin-Resistant Staphylococcus capitis with Reduced Vancomycin Susceptibility Causes Late-Onset Sepsis in Intensive Care Neonates

isolated from the blood of NICU infants and compared these data to adult patients. element, and constantly showed either vancomycin resistance (37.5%) or heteroresistance (62.5%). Conversely, the isolates that were collected outside of the NICU were genetically diverse and displayed much lower rates of vancomycin resistance and heteroresistance (7.7% and 23.1%, respectively). strains has spread into several French NICUs. These isolates exhibit reduced susceptibility to vancomycin, which is the most widely used antimicrobial agent in the NICU setting

La poétique de la morbidité dans les romans de Joris-Karl Huysmans et Michel Houellebecq

The poetics of morbidity in Joris-Karl Huysmans and Michel Houellebecq novels.Joris-Karl Huysmans is a XIX th Century novelist having belonged to the naturalistic trend whose figurehead is no one other than Emile Zola's. However, his literary universe will distance itself compared to the standards of naturalistic novel to explore other underground routes characterized by peculiarity and originality, it will be then classified among the most representative novelists of the ‘decadentist' movement through, in particular his touchstone novel ‘À rebours' said ‘neurosis novel'. Michel Houellebecq is a French novelist of the XX-XXIth century, known to address, in his novels, sensitive issues related mainly to the decline of western civilization. His novels (from "whatever" to "serotonine") are focused in particular on cold and objective analysis on the contemporary French society state (thus by western extension) via the staging of weakened characters both psychically and physically, projected in a society consumed by wild liberalism and with which they cannot interact. Comparisons between the literary universes of the two authors will be done through the prism of morbidity. Indeed, both in Michel Houellebecq and Joris-Karl Huysmans, morbidity that is the diverse manifestations of the disease (whether psychic or physical) the determining factor in the construction of their intrigues. Furthermore, a recurrent malaise seems pulling constantly the characters of both authors so that it tends to influence directly their relation with their immediate environments. Therefore, their perception of time, space, art, morality seems constantly impregnated with permanent pessimism.Huysmans est un romancier du XIXème siècle ayant appartenu au courant naturaliste dont la figure de proue n'était autre que celle d’Émile Zola. Cependant, son univers littéraire prendra ses distances par rapport aux canons du roman naturaliste pour explorer d'autres voies souterraines se caractérisant par la singularité et l'originalité. Il sera ainsi classé parmi les romanciers les plus représentatifs du mouvement "décadentiste", à travers notamment son roman phare " À rebours", dit "le roman de la névrose." Michel Houellebecq est un romancier français du XX-XXIème siècle, connu pour aborder, dans ses romans, des thématiques sensibles en rapport essentiellement avec le déclin de la civilisation occidentale. Ses romans (d' "Extension du domaine de la lutte" à "Sérotonine") sont axés notamment sur une analyse froide et objective de l'état de la société française (donc, par extension, occidentale) contemporaine via la mise en scène de personnages affaiblis tant psychiquement que physiquement, projetés dans une société rongée par un libéralisme sauvage et avec laquelle ils n'arrivent plus à interagir. La comparaison entre les univers littéraires des deux auteurs se fera à travers le prisme de la morbidité. En effet, tant chez Michel Houellebecq que Joris-Karl Huysmans, la morbidité c'est-à-dire les diverses manifestations de la maladie (qu'elle soit de nature psychique ou physique) est un facteur déterminant dans la construction de leurs intrigues. De plus, un mal-être récurrent semble tirailler sans cesse les personnages des deux auteurs si bien qu'il a tendance à influer directement sur leur rapport avec leurs environnements immédiats. Ainsi, leur perception du temps, de l'espace, de l'art, de la morale semble constamment imprégnée par un pessimisme permanent

Lp harmonic analysis for differential-reflection operators

International audienceWe introduce and study differential-reflection operators$\Lambda_{A, \varepsilon}$ acting on smooth functions defined on $\mathbb R.$ Here $A$ is a Sturm-Liouville function with additional hypotheses and $\varepsilon\in \mathbb R.$ For special pairs $(A,\varepsilon),$ we recover Dunkl's, Heckman's and Cherednik's operators (in one dimension). As, by construction, the operators $\Lambda_{A, \varepsilon}$ are mixture of ${\rm d}/{\rm d}x$and reflection operators, we prove the existence of an operator $V_{A,\varepsilon}$ so that $\Lambda_{A, \varepsilon}\circ V_{A,\varepsilon}=V_{A,\varepsilon}\circ {\rm d}/{\rm d}x.$ The positivity of the intertwining operator $V_{A,\varepsilon}$ is also established. Via the eigenfunctions of $\Lambda_{A,\varepsilon},$ we introduce a generalized Fourier transform $\mathcal F_{A,\varepsilon}.$ For $-1\leq \varepsilon\leq 1$ and $0 < p \leq \frac{2}{1+\sqrt{1-\varepsilon^2}},$ we develop an $L^p$-Fourier analysis for $\mathcal F_{A,\varepsilon},$ and then we prove an $L^p$-Schwartz space isomorphism theorem for $\mathcal F_{A,\varepsilon}$.Details of this paper will be given in another article

Uncertainty principles and characterization of the heat kernel for certain differential-reflection operators

International audienceWe prove various versions of uncertainty principles for a certain Fourier transform $\mathcal F_A.$ Here $A$ is a Chébli function (i.e. a Sturm-Liouville function with additional hypotheses). We mainly establish an analogue of Beurling's theorem, and its relatives such as theorems of type Gelfand-Shilov, Morgan's, Hardy's, and Cowling-Price, for $\mathcal F_A,$ and relating them to the characterization of the heat kernel corresponding to $\mathcal F_A.$ Heisenberg's and local uncertainty inequalities were also proved

First Report of Erannis defoliaria on Quercus sp. in North West of Tunisia

Erannis defoliaria, a spring-feeding moth, caused severe defoliation during springs 2009 and 2010. Larvae were collected from Quercus suber in northwestern forest of Tunisia: Bellif and Ain El Baya. Caterpillars of E. defoliaria were also observed feeding on Q. canariensis, Q. afares and other shrub species such as Pistacia lentiscus, Erica arborea, and E. multiflora. In this paper, we present a first report of this pest in Tunisia

A Context-Based Approach for Real-Time Adaptation Need Detection

International audienceThe increasingly dynamic and changing environment in which business processes are evolving requires companies to adapt them frequently. Thus, we propose in this paper a new context-based approach recommending to analyze well the environmental changes. This approach recommends to structure knowledge required for process adaptation need in accordance with our BPMN4V-Context meta-model, which supports the modeling of the operating environment, using the context along with the versions of the model of each BPMN process and their use conditions. It also advocates (i) a filtering activity to retain only significant context changes in the monitored data, as low-level context parameters, (ii) a reasoning activity to deduce high-level context parameters from filtered low-level ones, enhancing the current situation of running processes and (iii) examining the current situation before its analysis in order to resolve problems related to the used units and synonym values. Finally, the feasibilit y and applicability of this approach is demonstrated by a case study from the crisis domain and two performance tests