Rabat, Morocco
Rabat, Morocco
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Korytov M.,French National Center for Scientific Research | Budagosky J.A.,University of Valencia | Brault J.,French National Center for Scientific Research | Huault T.,French National Center for Scientific Research | And 5 more authors.
Journal of Applied Physics | Year: 2012

The capping of GaN quantum dots (QDs) with an Al 0.5Ga 0.5N layer is studied using transmission electron microscopy and atomic force microscopy in combination with theoretical calculations. The capping process can be divided into several well-distinguishable stages including a QD shape change and a local change of the Al 0.5Ga 0.5N capping layer composition. The phase separation phenomenon is investigated in relation with the capping layer thickness. Amount of the chemical composition fluctuations is determined from separate analysis of scanning transmission electron microscopy and high-resolution transmission electron microscopy images. The local distortion of atomic lattice in the QD surroundings is measured by high-resolution electron microscopy and is confronted with theoretically calculated strain distributions. Based on these data, a possible mechanism of alloy demixing in the Al 0.5Ga 0.5N layer is discussed. © 2012 American Institute of Physics.

El Bouayadi R.,University Mohammed Premier | Korytov M.,Leibniz Institute For Kristallzuchtung | van Aken P.A.,Max Planck Institute for Intelligent Systems (Stuttgart) | Vennegues P.,French National Center for Scientific Research | Benaissa M.,CNRST
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2014

The purpose of this study is to use high-angle annular-dark-field simulation to quantify aluminum fluctuation across the interface formed by a GaN-quantum dot and an AlGaN barrier layer. For this aim, a basic methodology with theoretical/numerical simulations has been carried out using nanometric, but not atomic, resolution range. A simple multislice method, based on simulations of the HAADF intensity scattered by a GaN/AlGaN interface was performed. Enrichment of aluminum near the GaN/AlGaN interface was confirmed by HAADF simulation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

d'Acremont E.,CNRS Paris Institute of Earth Sciences | Gutscher M.-A.,French National Center for Scientific Research | Rabaute A.,CNRS Paris Institute of Earth Sciences | Mercier de Lepinay B.,University of Nice Sophia Antipolis | And 14 more authors.
Tectonophysics | Year: 2014

Two recent destructive earthquakes in 1994 and 2004 near Al Hoceima highlight that the northern Moroccan margin is one of the most seismically active regions of the Western Mediterranean area. Despite onshore geodetic, seismological and tectonic field studies, the onshore-offshore location and extent of the main active faults remain poorly constrained. Offshore Al Hoceima, high-resolution seismic reflection and swath-bathymetry have been recently acquired during the Marlboro-2 cruise. These data at shallow water depth, close to the coast, allow us to describe the location, continuity and geometry of three active faults bounding the offshore Nekor basin. The well-expressed normal-left-lateral onshore Trougout fault can be followed offshore during several kilometers with a N171°E ± 3° trend. Westward, the Bousekkour-Aghbal normal-left-lateral onshore fault is expressed offshore with a N020°E ± 4° trending fault. The N030°E ± 2° Bokkoya fault corresponds to the western boundary of the Plio-Quaternary offshore Nekor basin in the Al Hoceima bay and seems to define an en échelon tectonic pattern with the Bousekkour-Aghbal fault. We propose that these three faults are part of the complex transtensional system between the Nekor fault and the Al-Idrissi fault zone. Our characterization of the offshore expression of active faulting in the Al Hoceima region is consistent with the geometry and nature of the active fault planes deduced from onshore geomorphological and morphotectonic analyses, as well as seismological, geodetic and geodynamic data. © 2014 Elsevier B.V.

Amadine O.,MASCIR Foundation | Amadine O.,Hassan II University | Maati H.,MASCIR Foundation | Maati H.,Hassan II University | And 8 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2014

CuCeO2 catalytic nanomaterials have been synthesized by impregnation of ceria by copper acetate, followed by reduction and calcination under nitrogen. The components of these nanomaterials were characterized by means of XRD, XPS, N2 adsorption/desorption, TGA, SEM, and TEM microscopy techniques. The XRD spectra of ceria and CuCeO2-1 (3.4 wt% copper loading) revealed a slight shift of the position of the planes with a small increase of the crystal lattice parameters, which can be explained by an eventual insertion of Cu0 in interstitial sites and/or a partial substitution of Ce4+ by Cu2+. CuCeO2 nanomaterials were found to be efficient catalysts for the N-arylation of indole with various aryl bromides to produce good yields of the desired products. The decrease in the catalytic activity of the catalyst during the reuse was probably due to oxidation of Cu0 to Cu2+ and its poisoning of KBr that was formed in situ. © 2014 Elsevier B.V. All rights reserved.

Ramananarivo H.R.,MAScIR Foundation | Ramananarivo H.R.,Mohammed V University | Abdelouahdi K.,CNRST | Abdelouahdi K.,Hassan II University | And 6 more authors.
European Journal of Inorganic Chemistry | Year: 2012

Zirconia nanoparticles (NPs) with a pure tetragonal phase, stable at high temperatures and with hierarchical pore networks, are synthesized from gelling alginate by complexation of zirconium ions within a fibrous cross-linked biopolymer. The concentration of precursor significantly affected the structural stability, crystal size, and crystal phase of the final material. The zirconia NPs were characterized by thermogravimetric analyses, nitrogen adsorption-desorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The method developed herein is straightforward as well as flexible and can pave the way to a host of hierarchical materials for current nanotechnologies. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Benaissa M.,CNRST | Korytov M.,French National Center for Scientific Research | Van Aken P.A.,Max Planck Institute for Intelligent Systems (Stuttgart) | Vennegues P.,French National Center for Scientific Research
MATEC Web of Conferences | Year: 2013

To shed light on these confined properties, a technique with a high energy-and-spatial resolution is of absolute need. Modern transmission electron microscopy (TEM) is the most suitable technique for a direct measurement of optical and structural properties at a nanometer scale. Thanks to the successful construction of aberration corrected transmission electron microscopes, the mapping of atomic positions with high accuracy becomes a routine experiment enabling therefore a more intuitive interpretation of structural deformation (strain). In addition, the recent development in energy-filters, especially when coupled to monochromated electron-beams, measurements of physical properties are achieved with unprecedented performances. The case of individual buried GaN/(AlGaN) quantum dots is discussed. © Owned by the authors, published by EDP Sciences, 2013.

Dagdougui H.,University of Genoa | Ouammi A.,CNRST | Sacile R.,University of Genoa
Proceedings - 2012 7th International Conference on System of Systems Engineering, SoSE 2012 | Year: 2012

Grid integration of wind power plants is becoming the main growing form of electricity generation among renewable energies. Recently, more interest is given to microgrids due to its potential benefits. The optimal operation of interconnected microgrids aims the matching of energy production with a dynamic load. In this paper, a control strategy for the wind power exchanges in a network of microgrids is formalized and tested on a Moroccan case study. The control variables are the instantaneous flows of wind power in the network of microgrids. The state is represented by the energy stored in each microgrid. This paper aims to minimize the variations of the energy stored in each storage device from a reference value, as well as to minimize the exchange of power between the microgrids. © 2012 IEEE.

Ouammi A.,CNRST | Zejli D.,CNRST | Dagdougui H.,University of Genoa | Sacile R.,University of Genoa
Proceedings - 2012 7th International Conference on System of Systems Engineering, SoSE 2012 | Year: 2012

An artificial neural network (ANN) model is used to forecast the annual wind speeds and solar irradiation in Morocco. Solar irradiation data are taken from the new Satellite Application Facility on Climate Monitoring (CM-SAF) - PVGIS database. The annual wind speed data are taken from (CDER, 2007). In this paper, the data are inferred using an ANN algorithm to establish a forward/reverse correspondence between the longitude, latitude, elevation, solar irradiation and wind speed. Specifically, for the ANN model, a three-layered, backpropagation standard ANN classifier is considered consisting of three layers: input, hidden and output layer. The learning set consists of the normalised longitude, latitude, elevation and the normalised mean annual wind speed of 20 sites and the normalised mean annual solar irradiation of 41 Moroccan sites. The testing set consists of patterns just represented by the input component, while the output component is left unknown and its value results from the ANN algorithm for that specific input. The results are given in the form of annual wind speed and solar irradiation maps. They indicate that the method could be used by researchers or engineers to provide helpful information for decision makers in terms of site selection, design and planning of new solar and/or wind power plants. © 2012 IEEE.

Bokov P.,University Paris Diderot | Flaud P.,University Paris Diderot | Bensalah A.,CNRST | Fullana J.-M.,CNRS Jean Le Rond d'Alembert Institute | Rossi M.,CNRS Jean Le Rond d'Alembert Institute
Journal of Biomechanical Engineering | Year: 2013

Computational hemodynamic models of the cardiovascular system are often limited to finite segments of the system and therefore need well-controlled inlet and outlet boundary conditions. Classical boundary conditions are measured total pressure or flow rate imposed at the inlet and impedances of RLR, RLC, or LR filters at the outlet. We present a new approach based on an unidirectional propagative approach (UPA) to model the inlet/outlet boundary conditions on the axisymmetric Navier-Stokes equations. This condition is equivalent to a nonreflecting boundary condition in a fluid-structure interaction model of an axisymmetric artery. First we compare the UPA to the best impedance filter (RLC). Second, we apply this approach to a physiological situation, i.e., the presence of a stented segment into a coronary artery. In that case a reflection index is defined which quantifies the amount of pressure waves reflected upon the singularity. Copyright © 2013 by ASME.

Bensalah M.O.,Mohammed V University | Chakchak H.,CNRST | Ghazali A.,Mohammed V University | Sadoune Z.,Mohammed V University
International Review of Mechanical Engineering | Year: 2011

In this work, we study the shape memory alloys (SMA) micromechanical behaviour in the perfect transformation plasticity. This study is based on the kinematical description of the physical mechanisms at the origin of the phenomenon, and on the thermodynamical analysis of the irreversible processes presented by these alloys in such a transformation. The pseudoelastical behaviour of SMA is described by defining a pseudoelastical potential through the Gibbs theory, and by application of the second principle of the thermodynamic. This approach allowed us to incorporate the change of the martensite variants shape in such thermomechanical behaviour and to analyse the hysteretic behaviour of these materials. © 2011 Praise Worthy Prize S.r.l. - All rights reserved.

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