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Besson R.,Lille University of Science and Technology | Favergeon L.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
Journal of Physical Chemistry C | Year: 2013

In spite of its wide use, the properties of the CaO/CaCO3 system are still far from being understood, especially the mechanisms underlying the transition between both phases. To investigate this issue, important in practice for storage devices, we employ first-principles atomic-scale simulations of the solid-gas interactions between CO2 and CaO, by considering insertion of CO2 within the subsurface, in configurations characteristic of calcite surface nucleation. Comparing the (001) and (111) surfaces demonstrates that nucleation should be strongly surface-selective, with a sharp preference for (111), and an important role of the CO2 arrangement in the surface layer. To interpret these results, especially the important structural instabilities detected, we investigate the elastic properties of coherent CaO/CaCO3 layered systems. This reveals the special role played by the (111) interface orientation and confirms the behavior detected at the atomic scale. From our study, we propose a mechanism for calcite nucleation as well as a plausible explanation for the degradation of performances crippling the CaO-based devices used for CO2 storage. © 2013 American Chemical Society. Source


Demanget N.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
Annals of biomedical engineering | Year: 2012

Stent-grafts (SGs) are commonly used for treating abdominal aortic aneurysms (AAAs) and numerical models tend to be developed for predicting the biomechanical behavior of these devices. However, due to the complexity of SGs, it is important to validate the models. In this work, a validation of the numerical model developed in Demanget et al. (J. Mech. Behav. Biomed. Mater. 5:272-282, 2012) is presented. Two commercially available SGs were subjected to severe bending tests and their 3D geometries in undeformed and bent configurations were imaged from X-ray microtomography. Dedicated image processing subroutines were used in order to extract the stent centerlines from the 3D images. These skeletons in the undeformed configurations were used to set up SG numerical models that are subjected to the boundary conditions measured experimentally. Skeletons of imaged and deformed stents were then quantitatively compared to the numerical simulations. A good agreement is found between experiments and simulations. This validation offers promising perspectives to implementing the numerical models in a computer-aided tool and simulating the endovascular treatments. Source


Gondran N.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
Ecological Indicators | Year: 2012

Ecological footprint calculation methodology is generally well defined on a national scale. It is also proposed by several authors as a corporate sustainability metric, yet for this scale, there is no consensus method. The aim of this paper is to identify the consequences of such methodological liberties within the ecological footprint estimation and its use as a decision aid tool on the scale of a public organization. The method was developed and validated for the Vanoise National Park which undertook to reduce its ecological footprint by 10% between 2009 and 2007. The methodological liberties inherent to ecological footprint analysis on an organization scale generate methodological choices that may influence the results in terms of environmental impact hierarchy and priority of actions. Therefore, such analysis requires transparency in the methodological choices behind the calculation and the involvement of the end-users in these choices. © 2011 Elsevier Ltd. Source


Malliaras G.G.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
Biochimica et Biophysica Acta - General Subjects | Year: 2013

Background: This issue of "Biochimica et Biophysica Acta - General Subjects" is dedicated to organic bioelectronics, an interdisciplinary field that has been growing at a fast pace. Bioelectronics creates tremendous promise, excitement, and hype. The application of organic electronic materials in bioelectronics offers many opportunities and is fuelled by some unique features of these materials, such as the ability to transport ions. Scope of review: This is a perspective on the history and current status of the field. Major conclusions: Organic bioelectronics currently encompasses many different applications, including neural interfaces, tissue engineering, drug delivery, and biosensors. The interdisciplinary nature of the field necessitates collaborations across traditional scientific boundaries. General significance: Organic bioelectronics is a young and exciting interdisciplinary field. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine. © 2012 Elsevier B.V. Source


Louly M.-A.,King Saud University | Dolgui A.,Ecole Nationale Superieure des Mines de Saint - Etienne CMP
International Journal of Production Economics | Year: 2013

This study deals with Material Requirement Planning (MRP) software parameterization under uncertainties. The actual lead time has random deviations; so it can be considered as a random variable. MRP approach with Periodic Order Quantity (POQ) policy is considered. The aim is to find the optimal MRP time phasing corresponding to each periodicity of the POQ policy. This is a crucial issue in supply planning with MRP approach because inappropriate planned lead times under lead time uncertainties invariably lead to large and costly inventories or insufficient customer service levels. The proposed model and algorithms minimize the sum of the setup and holding costs while satisfying a constraint on the service level. Our approach does not need to employ the commonly used normal probability distributions. Instead, its originality is in finding a closed form of the objective function, valid for any probability distribution of the actual lead times. © 2011 Elsevier B.V. Source

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