ISMANS

Le Mans, France
Le Mans, France
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Deng W.,ISMANS | Deng W.,Central China Normal University | Deng W.,University of Maine, France | Li W.,Central China Normal University | And 4 more authors.
Physica A: Statistical Mechanics and its Applications | Year: 2011

The exponential degree distribution has been found in many real world complex networks, based on which, the random growing process has been introduced to analyze the formation principle of such kinds of networks. Inspired from the non-equilibrium network theory, we construct the network according to two mechanisms: growing and adjacent random attachment. By using the KolmogorovSmirnov Test (KST), for the same number of nodes and edges, we find the simulation results are remarkably consistent with the predictions of the non-equilibrium network theory, and also surprisingly match the empirical databases, such as the Worldwide Marine Transportation Network (WMTN), the Email Network of University at Rovira i Virgili (ENURV) in Spain and the North American Power Grid Network (NAPGN). Our work may shed light on interpreting the exponential degree distribution and the evolution mechanism of the complex networks. © 2011 Elsevier B.V. All rights reserved.


Chauke H.R.,University of Limpopo | Minisini B.,ISMANS | Drautz R.,Ruhr University Bochum | Nguyen-Manh D.,Babcock Power | And 3 more authors.
Intermetallics | Year: 2010

The deleterious low-temperature tetragonal phases in prototypical Pt-based superalloys have variously been reported as taking the tI16-U3Si (DOc), tI16-Ir3Si (DOc′) and tP16-Pt3Ga structure-types in contrast to the high-temperature cubic cP4-Cu3Au (L12) phase. We have investigated the relative stability of these four structure-types at absolute zero by using density functional theory. We find that the ground state of stoichiometric Pt3Al is tP16-Pt3Ga and that the other three lattices are mechanically unstable at absolute zero. Experiments are needed to measure the internal displacement parameters of these three competing tetragonal phases. © 2009 Elsevier Ltd. All rights reserved.


Demianenko P.,CNRS Le Mans Institute of Molecules and Materials | Minisini B.,ISMANS | Lamrani M.,ISMANS | Poncin-Epaillard F.,CNRS Le Mans Institute of Molecules and Materials
Materials Today Communications | Year: 2015

Interpenetrating polymer network hydrogels based on fluoro-, siloxane-acrylates and N-vinylpyrrolidone were synthesized using simultaneous photopolymerization technique in presence of poly(ethylene glycol diacrylate) as cross-linker. These hydrogels were characterized by Fourier-transform infrared spectroscopy and by their swelling properties. Evidence of the semi-IPN structure was shown thanks to the selective chemical attack on the cross-linker. Poly(ethylene glycol diacrylate) crosslinks of prepared hydrogels were attacked by concentrated basic solution leading to the hydrolysis of the poly(ethylene glycol diacrylate) molecules and the degradation of the polymer network. The solid residue and the liquid phase after degradation were analyzed by gas chromatography with mass spectrometry analyzer and by FTIR spectroscopy. These analyses gave evidence of the presence of non-crosslinked poly(N-vinylpyrrolidone) chains in the acrylate network. Henceforth, the synthesized hydrogel should be associated to a semi-IPN structure. © 2015 Elsevier Ltd.


El Mendili Y.,University of Nantes | Minisini B.,ISMANS | Abdelouas A.,University of Nantes | Bardeau J.-F.,CNRS Le Mans Institute of Molecules and Materials
RSC Advances | Year: 2014

The mackinawite mineral was prepared as a carbon steel corrosion product in sulfidogenic waters at 90 °C after 2 months. The tetragonal crystal structure of the material was confirmed by Rietveld refinement of X-ray diffraction (XRD) data, and vibrational modes were analysed by micro-Raman spectroscopy. Despite a large number of studies on the formation and the stability of tetragonal mackinawite, the interpretation of the Raman spectra remains uncertain. In the present study, we report on the first calculation of the Raman-active vibrational modes of mackinawite using Density Functional Perturbation Theory and direct methods with BLYP + dispersion correction. Based on the comparison between calculated and experimental results, the four fundamental vibrational modes were assigned as 228 cm-1 (B 1g), 246 cm-1 (Eg), 373 cm-1 (A 1g) and 402 cm-1 (Eg). © the Partner Organisations 2014.


Le Mehaute A.,ISMANS | El Kaabouchi A.,ISMANS | Nivanen L.,ISMANS
Computers and Mathematics with Applications | Year: 2010

Riemann's conjecture is understood as a consequence of the dσ / d tσ-fractional order differential dynamics which seeds a constructive approach to the zeta function. A morphism between different representations of the dynamics reveals a hidden correlation between a phase angle ψ0 (σ) = (π / 2) (1 - σ) introduced by the real term of the power σ and the complex part θ. © 2009 Elsevier Ltd. All rights reserved.


Minisini B.,ISMANS | Vathonne E.,ISMANS | Chivas-Joly C.,French National Laboratory of Metrology and Testing | Lopez-Cuesta J.-M.,Ecole des Mines d'Ales
Journal of Molecular Modeling | Year: 2013

DFT calculations, with VWN exchange correlation functional and double numeric basis set, were used to evaluate the energies required for the scission reactions taking place in the initial stage of the thermal degradation of Poly(methyl methacrylate) (PMMA) in the presence of a carbon nanotube (CNT). Side group and main chain scissions were investigated. The results averaged from five configurations of pure PMMA (DP = 5) were used as references and compared to the results obtained for the five same configurations of PMMA grafted on three carbon nanotubes of similar diameter (1.49 nm). The bond dissociation energies (BDE) of main chain scission evaluated for grafted PMMA was 4 % less endothermic than for pure PMMA. These results seemed independent of the tested chirality (11,11); (12,10) and (16,5) of the carbon nanotubes. Comparisons with the BDE of the weakest bonds due to intrinsic defaults (head to head and unsaturated end chain) were performed. [Figure not available: see fulltext.] © 2012 Springer-Verlag.


Hassan H.,TREFLE laboratory Bordeaux1 | Regnier N.,TREFLE laboratory Bordeaux1 | Pujos C.,ISMANS | Arquis E.,TREFLE laboratory Bordeaux1 | Defaye G.,TREFLE laboratory Bordeaux1
Applied Thermal Engineering | Year: 2010

Injection molding is one of the most exploited industrial processes in the production of plastic parts. Shrinkage behavior of a molded plastic part plays an important role in determining final dimensions of the part. In this paper, the effect of the cooling system on the shrinkage rate of a polystyrene product during injection molding is carried out. A compressible fluid model for the physical system is presented. A finite volume numerical solution is used for the solution of the physical model. A validation of the numerical model in case of square cavity filled with polymer material is presented. The compressibility behavior of polymer material observed by the pressure, volume, and temperature for the state equation (P-v-T equation) is represented by Tait's equation. A Cross type rheological model depending on the temperature and pressure is assumed for the polymer material. The studied configurations consist of a mold having T-shaped plastic part and four cooling channels. Different cooling channels' positions are assumed and the effect of their positions on the cooling process is studied. The results indicate a good agreement between the numerical solution and those of the literatures. They also, show that the position of the cooling channels has a great effect on final product temperature and the shrinkage rate distribution throughout the product. © 2010 Elsevier Ltd. All rights reserved.


Verchery G.,ISMANS
Mechanics of Composite Materials | Year: 2011

This paper aims at promoting laminate designs with specific stiffness properties: quasi-homogeneous, quasi-isotropic quasi-homogeneous, and thermally stable laminates. For this, the paper first discusses the concept of design, reviews the classical laminated plate theory and the usual design rules for laminates, and introduces the polar method for plane anisotropy. Then it develops rules and methods to design the stiffness properties that are looked for. In conclusion, it suggests that the classical design rules are too restrictive and that innovative designs should be explored for a better use of composites. © 2011 Springer Science+Business Media, Inc.


Bruyneel M.,LMS Samtech | Beghin C.,ISMANS | Craveur G.,ISMANS | Sosonkina M.,LMS Samtech
Structural and Multidisciplinary Optimization | Year: 2012

In this paper, an optimization procedure based on multi-phase topology optimization is developed to determine the optimal stacking sequence of laminates made up of conventional plies oriented at -45°, 0°, 45 and 90°. The formulation relies on the SFP (Shape Functions with Penalization) parameterization, in which the discrete optimization problem is replaced by a continuous approach with a penalty to exclude intermediate values of the design variables. In this approach, the material stiffness of each physical ply is expressed as a weighted sum over the stiffness of the candidate plies corresponding to -45°, 0°, 45 and 90? orientations. In SFP, two design variables are needed for each physical ply in the laminate to parameterize the problem with respect to the 4 candidate orientations. Even if only constant stiffness laminates of constant thickness are considered in this paper, specific design rules used in aeronautics for composite panels (i.e., no more than a maximum number of consecutive plies with the same orientation in the stacking sequence) are however formulated and taken into account in the optimization problem. The methodology is demonstrated on an application. It is discussed how the different design rules can affect the solution. © Springer-Verlag 2012.


PubMed | ISMANS and CNRS Le Mans Institute of Molecules and Materials
Type: Journal Article | Journal: Journal of molecular modeling | Year: 2016

Different static properties have been calculated with COMPASS force field for polyacrylamide, poly(2-hydroxyethylacrylate) (HEA), poly(2-hydroxyethylmethacrylate) (HEMA), poly(glycidylmethacrylate) (GMA), polyethylene glycol (PEG), and poly(2,2,2-trifluoroethylmethacrylate) (TFEM). For each polymers, the calculated values were averaged on five equilibrated configurations of amorphous cell composed of one atactic chain containing 100 repeat units. The ranking obtained from the densities calculated at 300K is TFEM>HEAxpolycrylamide>HEMAGMA>PEG. Concerning the glass transition temperature we have obtained polyacrylamide>HEMAGMAHEA>PEG, and polyacrylamide>HEMAHEA>GMAPEG>TFEM for the bulk modulus. The calculated results, when available, have been compared with experimental data coming from literature.

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