University Of Djibouti

Clemenceau, Djibouti

University Of Djibouti

Clemenceau, Djibouti
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Roble H.E.,University of Djibouti | Hoarau Y.,University of Strasbourg | Dusek J.,University of Strasbourg | Mahamoud N.Y.,University of Djibouti
ARPN Journal of Engineering and Applied Sciences | Year: 2016

The study undertaken in this article is to develop a reliable and comprehensive numerical modelling of particle transport in pulmonary flow based on the use of CFD-ACE code of commercial calculation. This code includes a fluid solver that solves the Navier-Stokes in a finite volume formulation. The CFD-GEOM software was used to create the 3D surfaces of the generic model geometry Weibel and thereby generate the tetrahedral mesh unstructured finite volume. The air flow is assumed laminar stationary (or unsteady only in bronchial models) and incompressible, the particles of diameter 5 micrometers are spherical and non-interacting. So we have successfully modelled the flows and the transport of particles in simple configurations (Model Weibel) and realistic configuration (rat lung) and what we can say is that the simulation , although expensive in terms of computer memory and time (specially for particle deposition), does not present insurmountable difficulties. As against obtaining a realistic geometry and the associated mesh generation remains a delicate stage. © 2006-2016 Asian Research Publishing Network (ARPN).

Kileh Wais M.,French National Institute for Agricultural Research | Kileh Wais M.,University Of Djibouti | Elsen J.M.,French National Institute for Agricultural Research
Journal of Animal Breeding and Genetics | Year: 2012

QTL detection using the regression of phenotypes on transmission probability is largely used when large families are available. In three generations designs, the use of a 'de-regressed proof' as a phenotype to be analysed was proposed by Weller (1990) and Tribout (2008). Our work generalizes this approach. A score (that we define as a 'generalized de-regressed proof') is described, which combines performance phenotypes recorded in multigenerational offspring of genotyped individuals. Estimation of the QTL effect on this score with a simple regression is unbiased. The link between this score and the BLUP animal model of the polygenic effect is demonstrated. The theory is developed and two simple examples illustrate how this technique can be implemented. © 2011 Blackwell Verlag GmbH.

Pays O.,University of Angers | Pays O.,University Of Reims | Pays O.,French National Institute for Agricultural Research | Fortin D.,Laval University | And 2 more authors.
PLoS ONE | Year: 2012

Despite the large number of movement studies, the constraints that grouping imposes on movement decisions remain essentially unexplored, even for highly social species. Such constraints could be key, however, to understanding the dynamics and spatial organisation of species living in group fusion-fission systems. We investigated the winter movements (speed and diffusion coefficient) of groups of free-ranging roe deer (Capreolus capreolus), in an agricultural landscape characterised by a mosaic of food and foodless patches. Most groups were short-lived units that merged and split up frequently during the course of a day. Deer groups decreased their speed and diffusion rate in areas where food patches were abundant, as well as when travelling close to main roads and crest lines and far from forests. While accounting for these behavioural adjustments to habitat features, our study revealed some constraints imposed by group foraging: large groups reached the limit of their diffusion rate faster than small groups. The ability of individuals to move rapidly to new foraging locations following patch depression thus decreases with group size. Our results highlight the importance of considering both habitat heterogeneity and group dynamics when predicting the movements of individuals in group fusion-fission societies. Further, we provide empirical evidence that group cohesion can restrain movement and, therefore, the speed at which group members can explore their environment. When maintaining cohesion reduces foraging gains because of movement constraints, leaving the group may become a fitness-rewarding decision, especially when individuals can join other groups located nearby, which would tend to maintain highly dynamical group fusion-fission systems. Our findings also provide the basis for new hypotheses explaining a broad range of ecological patterns, such as the broader diet and longer residency time reported for larger herbivore groups. © 2012 Pays et al.

Aaboubi O.,CNRS Laboratory of Engineering and Materials Science | Ali-Omar A.-Y.,University Of Djibouti | Dzoyem E.,CNRS Laboratory of Engineering and Materials Science | Marthe J.,CRITT MTDS | Boudifa M.,CRITT MTDS
Journal of Power Sources | Year: 2014

To develop large scale use of hydrogen and fuel cells as a renewable energy source it is need to increase their durability and reduce their cost mainly due to the use of precious metals. We have examined new type of the low cost binary nickel-manganese (Ni-Mn) catalysts electrodeposited from ammonium chloride bath onto copper substrates. By varying bath composition, polarization potential and essentially bath temperature the operating deposition conditions were optimized to produce Ni-Mn coatings with high active surface (e.g. spongy aspect). The outstanding catalytic activity, the durability and the versatility of the deposited films have been characterized in basic media using several electrochemical processes, such as hydrogen evolution reaction (HER), water oxidation reaction (OER) and ethanol oxidation reaction (EOR). © 2014 Elsevier B.V. All rights reserved.

Aaboubi O.,British Petroleum | Ali Omar A.Y.,British Petroleum | Ali Omar A.Y.,University Of Djibouti | Franczak A.,Catholic University of Leuven | Msellak K.,British Petroleum
Journal of Electroanalytical Chemistry | Year: 2015

In the preliminary paper, devoted to the study of magnetic field effects on the catalytic properties of nickel-molybdenum (Ni-Mo) system for hydrogen evolution reaction (HER), we have shown that the main effect of a magnetic field is related to the deposits surface modifications. In the present paper the electrodeposition kinetics of Ni-Mo was investigated, using electrochemical impedance spectroscopy (EIS) and polarization curves methods with and without magnetic fields. The reaction path was proposed to account for the main features of the deposition kinetics (polarization curves and impedance diagrams). This involves the reduction of Ni(II) and Mo(IV) complexed species into compounds that can be included as a whole into the deposit or decomplexed to product alloys deposits. In both cases the charge transfers reactions occurred in more than two steps, coupled by adsorbed intermediates. The proposed model can also account for the current density dependency upon the potential value and the magnetic field intensity. © 2014 Elsevier B.V. All rights reserved.

PubMed | University Of Djibouti, University of Picardie Jules Verne and University of Paris Descartes
Type: Journal Article | Journal: Journal of athletic training | Year: 2016

Various continental sporting events have exposed team sports referees to different environmental conditions. Several studies have focused on strategies to prevent athlete performance impairment induced by heat or warm (or both) conditions, but few authors have investigated the effect of heat on referees performance. In a thermoneutral environment, referees physical activity induced mild 2.0% dehydration, which was responsible for reductions in physical, psychomotor, and cognitive performances. Therefore, the hydration status of referees should be taken into account to reduce referees errors and misjudgments in the heat.

Guedi A.O.,University Of Djibouti | Huchard M.,Montpellier University | Miralles A.,IRSTEA | Nebut C.,Montpellier University
Proceedings - IEEE International Enterprise Distributed Object Computing Workshop, EDOC | Year: 2013

The design of class models for information systems, databases or programming is a delicate process in which experts of the domain and designers have to identify and agree on the domain concepts. Formal Concept Analysis (FCA) has been proposed for supporting this collaborative work and fostering the emergence of higher level entities and the factorization of descriptions and behaviors. More recently, an extension of FCA, Relational Concept Analysis (RCA), has been designed to extend the scope of FCA to the emergence of higher level domain associations. FCA and RCA build a kind of normal form for models, in which the factorization is exhaustive, and the specialization order is adequate. The counterpart of these strong properties is a worst-case exponential theoretical complexity. In this paper, we study a practical application of RCA on several versions of a real class model in order to give precise figures about RCA and to detect which configurations are tractable. © 2013 IEEE.

Bexi I.,CNRS Paris Institute of Global Physics | Bexi I.,University of Djibouti | Chavanne X.,CNRS Paris Institute of Global Physics | Conejo E.,CNRS Paris Institute of Global Physics | Frangi J.-P.,CNRS Paris Institute of Global Physics
IEEE Transactions on Instrumentation and Measurement | Year: 2012

This paper describes the procedure to qualify an admittance meter as a permittivity meter and a conductivity meter sensor through validation with liquids over a range of relative permittivity r values from 1 to 80 and with operating frequencies f between 1 and 20 MHz. The sensor is a capacitor which consists of two parallel cylinders of 10-cm typical dimension. A circuit-based model of the sensor was previously calibrated against accurate electronic components. A discrepancy of 10% is found between the calibration with components and the validation with liquids. All potential errors have been carefully examined: parasitic impedances of the electronic circuit and leads, modifications of liquid permittivity rliq due to temperature influence, water contamination or relaxation effects, and possible fringing effects with the help of numeric simulations. Forty percent of the discrepancy results from the finite dimensions of the liquid-filled recipient. The fringing effects due to insulating rings at each end of the capacitor seem to be discarded. The analysis of the uncertainty on r sensor and ; sensor shows a relative uncertainty of 3%-5% due in large part to the numerical acquisition of high frequency. © 2012 IEEE.

Barreh K.A.,University of Djibouti | Abas Z.W.,University of Indonesia
Doctoral Student Consortium (DSC) - Proceedings of the 22nd International Conference on Computers in Education, ICCE 2014 | Year: 2014

As mobile learning has become ubiquitous, many higher education institutions have embarked on a number of mobile learning initiatives to support their traditional learning modes. The main purpose of this study is to provide a framework for mobile learning for the enhancement of learning in higher education based on the research conducted among students at the University of Djibouti. In order to meet the objective of this study, the research will use qualitative and quantitative research methods. While the entire gamut of mobile technologies and its academic applications needs to be considered, special emphasis and focus will be provided to Short Message Services (SMS) and most popular social network sites such as Facebook, which is widely used for recreation. This study highlights how mobile learning using SMS and Facebook could work hand-in hand with classroom learning in order to support student learning in higher education.

Mahamoud A.,University Of Djibouti | Mahamoud A.,École Centrale Nantes | Glumineau A.,École Centrale Nantes | Souleiman I.,University Of Djibouti
2009 European Control Conference, ECC 2009 | Year: 2015

This paper proposes a FDI strategy using high gain observers. Observers are often necessary for control purpose. It is possible to extend their application to disturbance estimation and FDI strategy. The observer is designed for a performance study on an induction motor in the framework of a specific induction motor Fault Diagnosis Benchmark. © 2009 EUCA.

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