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Douai, France

The École des Mines de Douai also called "École Nationale Supérieure des Mines de Douai " is a French National Graduate School of Engineering located in the city of Douai, close to Lille, North of France.Founded in 1878, the institute was originally a vocational school providing for the training needs of skilled workers "Maîtres-mineurs" for the coal mining industry. In the 1960s, it awarded its first engineering degree. Today, the Grande École des Mines de Douai trains high-level engineers and scientists in various technological fields.Despite its small size , it is a crucial part of the infrastructure of French industry.Its curricula include: Civil Engineering Energy for Industries Polymer and Composite materials Mechanical Engineering Industrial Engineering Electrical Engineering Computer Science Metrology and Quality Chemistry and EnvironmentTogether with Écoles des Mines in Nantes, Albi, Alès, Nancy, Saint-Étienne and Paris, the École des Mines de Douai forms the GEM network. The GEM Institute of Technology brings together 7 prestigious French engineering schools, offering programs that cover the entire range of science and technologies that are necessary for the development of industry.The École des Mines de Douai gives the opportunity to earn a double degree with the following universities : 23x15px Imperial College London 23x15px Georgia Institute of Technology 23x15px University of Delaware 23x15px École Polytechnique de Montréal 23x15px École de technologie supérieure 23x15px Tsinghua University 23x15px Shanghai Jiao Tong University 23x15px Hohai University 23x15px Audencia 23x15px Telecom Business School 23x15px Universidad Politécnica de Madrid 23x15px Federal University of Rio de Janeiro 23x15px UCL University Vittoria ↑ Wikipedia.

Nguyen Q.-H.,INSA Rennes | Hjiaj M.,INSA Rennes | Le Grognec P.,Ecole Des Mines de Douai
Journal of Sound and Vibration | Year: 2012

In this paper, an analytical procedure for free vibrations of shear-deformable two-layer beams with interlayer slip is developed. The effect of transverse shear flexibility of two layers is taken into account in a general way by assuming that each layer behaves as a Timoshenko beam element. Therefore, the layers have independent shear strains that depend indeed on their own shear modulus. This is the main improvement of the proposed model compared to existing models where the transverse shear flexibility is ignored or taken into account in a simplified way in which the shear strains of both layers are assumed to be equal whatever the shear modulus of the layers. In the proposed model, the two layers are connected continuously and the partial interaction is considered by assuming a continuous relationship between the interface shear flow and the corresponding slip. Based on these key assumptions, the governing differential equation of the problem is derived using Hamiltons principle and is analytically solved. The solutions for the eigenfrequencies and eigenmodes of four single span two-layer beams with classical Euler boundary conditions, i.e. pinned-pinned, clamped-clamped, clamped-pinned and clamped-free, are presented. Next, some numerical applications dealing with these four beams are carried out in order to compare the eigenfrequencies obtained with the proposed model against two existing models which consider different kinematic assumptions. Finally, a parametric study is conducted with the aim to investigate the influence of varying material and geometric parameters on the eigenfrequencies, such as shear stiffness of the connectors, span-to-depth ratios, flexural-to-shear moduli ratios and layer shear moduli ratios. © 2012 Elsevier Ltd. All rights reserved.

Lughofer E.,Johannes Kepler University | Sayed-Mouchaweh M.,Ecole Des Mines de Douai
Information Sciences | Year: 2015

We propose a new clustering method, which is dynamic in the sense that it updates its structure (cluster partition) permanently based on new incoming data samples. As it basically operates in single-pass and sample-wise manner without using time-intensive re-training phases, it is applicable for extracting clusters from on-line data streams. The approach builds upon an extended, dynamic version of evolving vector quantization, generalizing it to prototype clusters with convex (ellipsoidal) shapes in arbitrary positions. It includes incremental split-and-merge techniques in order to resolve cluster fusion and cluster delamination effects. The merging process is guided by geometrical criteria indicating overlapping clusters with joint homogeneity areas, and implements a fast fusion of two clusters fulfilling the criteria. The splitting process relies on concepts of seeking for heterogeneity (disjoint density areas) within already extracted clusters. This is based (1) on components (mixture models) identification while measuring their reliability (a) with the Bayesian information criterion (BIC) and (b) in terms of a proper convergence of the EM algorithm and (2) on an extended form of the Welch test for verifying whether the identified components are statistically independent - the extension concerns the integration of their mixing proportions. Finally, split-and-merge operations are able to automatically compensate inappropriate settings of the method's learning parameter, thus still being able to extract the desired cluster structure. Thus, our approach presents an attempt towards a parameter-free evolving clustering algorithm. This is an essential property as several trials with different settings are often not desired (in case of huge streams) or not possible at all (in case of on-line streams). Based on high-dimensional real-world clustering streams, our approach will be compared with alternative incremental as well as batch prototype-based clustering methods. The comparison will be based on the quality of the final obtained cluster partitions, the deviation of the extracted number of clusters to the real number, the sensitivity with respect to the most influencing learning parameters and the plug-and-play capability of the methods. © 2015 Elsevier Inc. All rights reserved.

Le Grognec P.,Ecole Des Mines de Douai | Nguyen Q.-H.,INSA Rennes | Hjiaj M.,INSA Rennes
International Journal of Solids and Structures | Year: 2012

This paper deals with the buckling behavior of two-layer shear-deformable beams with partial interaction. The Timoshenko kinematic hypotheses are considered for both layers and the shear connection (no uplift is permitted) is represented by a continuous relationship between the interface shear flow and the corresponding slip. A set of differential equations is obtained from a general 3D bifurcation analysis, using the above assumptions. Original closed-form analytical solutions of the buckling load and mode of the composite beam under axial compression are derived for various boundary conditions. The new expressions of the critical loads are shown to be consistent with the ones corresponding to the Euler-Bernoulli beam theory, when transverse shear stiffnesses go to infinity. The proposed analytical formulae are validated using 2D finite element computations. Parametric analyses are performed, especially including the limiting cases of perfect bond and no bond. The effect of shear flexibility is particularly emphasized. © 2011 Elsevier Ltd. All rights reserved.

Bellmann F.,Bauhaus University Weimar | Damidot D.,Ecole Des Mines de Douai | Moser B.,Bauhaus University Weimar | Skibsted J.,The Interdisciplinary Center
Cement and Concrete Research | Year: 2010

Tricalcium silicate (Ca3SiO5) with a very small particle size of approximately 50 nm has been prepared and hydrated for a very short time (5 min) by two different modes in a paste experiment, using a water/solid-ratio of 1.20, and by hydration as a suspension employing a water/solid-ratio of 4000. A phase containing uncondensed silicate monomers close to hydrogen atoms (either hydroxyl groups or water molecules) was formed in both experiments. This phase is distinct from anhydrous tricalcium silicate and from the calcium-silicate-hydrate (C-S-H) phase, commonly identified as the hydration product of tricalcium silicate. In the paste experiment, approximately 79% of silicon atoms were present in the hydrated phase containing silicate monomers as determined from 29Si{1H} CP/MAS NMR. This result is used to show that the hydrated silicate monomers are part of a separate phase and that they cannot be attributed to a hydroxylated surface of tricalcium silicate after contact with water. The phase containing hydrated silicate monomers is metastable with respect to the C-S-H phase since it transforms into the latter in a half saturated calcium hydroxide solution. These data is used to emphasize that the hydration of tricalcium silicate proceeds in two consecutive steps. In the first reaction, an intermediate phase containing hydrated silicate monomers is formed which is subsequently transformed into C-S-H as the final hydration product in the second step. The introduction of an intermediate phase in calculations of the early hydration of tricalcium silicate can explain the presence of the induction period. It is shown that heterogeneous nucleation on appropriate crystal surfaces is able to reduce the length of the induction period and thus to accelerate the reaction of tricalcium silicate with water. © 2010 Elsevier Ltd. All rights reserved.

Tiwari S.,Indian Institute of Technology Delhi | Bijwe J.,Indian Institute of Technology Delhi | Panier S.,Ecole Des Mines de Douai
Wear | Year: 2011

Fiber-matrix interfacial bonding plays a critical role in controlling performance properties of the composites. Carbon fibers have major constraint of chemical inertness with the matrix and need surface treatment to improve the adhesion with the matrix. In this work, gamma irradiation technique with varying doses (100-300 kGy) was employed to carbon fabric (CF) to develop composites with polyetherimide (PEI) matrix based on impregnation method followed by compression molding. Composites were characterized for interlaminar shear strength (ILSS) and adhesive wear studies against mild steel disc under various loads. Improvement in the friction and wear properties was correlated with the improvement in ILSS as a result of CF treatment. Higher the dosing, higher was the enhancement in ILSS and tribo-performance of composites. Fourier transform infrared spectroscopy (FTIR) indicated inclusion of functional groups (mainly carbonyl). SEM studies on fibers indicated roughening of the surface as a consequence of treatment. Both these factors were thought to be responsible for enhancing the fiber-matrix interface. For in depth analysis, various techniques such as fiber tension test, adhesion test and Raman spectroscopy analysis of CF were also exploited. © 2011 Elsevier B.V.

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