Influence of Wetting Properties on Diffusion in a Confined Fluid

We briefly discuss how the wetting properties of a fluid/solid interface can indirectly influence the diffusion properties of fluid confined between two solid walls. This influence is related to the variability of the hydrodynamic boundary conditions at the interface, which correlates to the wetting properties.Comment: Paper presented at the ILL workshop "Dynamics in confinment", Grenoble, January 2000 (http://www.ill.fr

Universal and non-universal features in coarse-grained models of flow in disordered solids

We study the two-dimensional (2D) shear flow of amorphous solids within variants of an elastoplastic model, paying particular attention to spatial correlations and time fluctuations of, e.g., local stresses. The model is based on the local alternation between an elastic regime and plastic events during which the local stress is redistributed. The importance of a fully tensorial description of the stress and of the inclusion of (coarse-grained) convection in the model is investigated; scalar and tensorial models yield very similar results, while convection enhances fluctuations and breaks the spurious symmetry between the flow and velocity gradient directions, for instance when shear localisation is observed. Besides, correlation lengths measured with diverse protocols are discussed. One class of such correlation lengths simply scale with the spacing between homogeneously distributed, simultaneous plastic events. This leads to a scaling of the correlation length with the shear rate as $\dot{\gamma}^{\frac{-1}{2}}$ in 2D in the athermal regime, regardless of the details of the model. The radius of the cooperative disk, defined as the near-field region in which plastic events induce a stress redistribution that is not amenable to a mean-field treatment, notably follows this scaling. On the other hand, the cooperative volume measured from the four-point stress susceptibility and its dependence on the system size and the shear rate are model-dependent.Comment: 17 page

Enterprise modelling : building a product lifecycle (PLM) model as a component of the integrated vision of the enterprise

Enterprise modelling has proved to be an efficient tool to study organisations structure and facilitate decision making. The enterprise is a complex system that is required to use its processes to generate value in a given environment (concurrent, market, suppliers and humanity). We focus on three management disciplines: Product Lifecycle Management (PLM), Supply Chain Management (SCM) and Customer Relationship Management (CRM). These business processes are so intertwined that the enterprise has to concentrate on the three to attain its economic objectives. To enhance the development of PLM, SCM and CRM models, the enterprise needs to capitalise the knowledge necessary to adapt and apply modelling techniques. Knowledge Management (KM) is a key factor to give a unified enterprise vision. Firstly, we propose an integrated enterprise model depicting the interactions between PLM, SCM, CRM and KM models. But a state of the art showed that PLM models are scarce. Most of the PLM models found depends strongly on the particular case studied and can not be used with other enterprises. After defining the most important components of the PLM vision, we propose to organise these components into a formalised way. The study of SCM and CRM models proved to be helpful to structure these components. Finally the validation methodology that is to be established in our coming research works is not only to be used with the PLM model presented in this paper but with SCM and CRM models also.Product Lifecycle Management (PLM), Enterprise modelling, Enterprise systems

Technological Responses of Neanderthals to Macroclimatic Variations (240,000–40,000 BP)

Using a database of 499 archaeological assemblages from 332 sites in Europe, we statistically test a model of the economic reactivity of the hunter-gatherer production system to climatic variations. This model predicts an increase in the diversity of lithic tools during harsh cold periods, in order to maintain carrying capacity, and a reduction during favorable climatic periods. Diversity was measured from the variations in flint tool distributions in traditional Bordes typological categories, using Shannon’s derived diversity index (D). Reactivity was measured in 190 archaeological assemblages from 103 sites of the Middle Paleolithic in Europe (mainly France). The Neanderthals show technological inertia in the development and use of lithic tools for 200,000 years, despite the four cool to cold macroclimatic periods they experienced

Systemic approach as a multi-criteria design method: healthcare R&D centre application

International audienceIn today's very competitive and changing environment, developing a competitive advantage is a huge challenge for companies. But it is not their single challenge. They have to be different from and always better than the others on a lot of criteria. Companies' performance has become multi-criteria; the performance can be for example scientific, societal, ethical or economical performance. In this context, companies that plan to create a new organisation or department have to think ahead all these strategic objectives to fulfil. This article presents a systemic approach for the multi-criteria design of a research centre, MIRCen (Molecular Imaging Research Centre). MIRCen is a research centre developed by the CEA (Commissariat à l'Energie Atomique) on preclinical imaging dedicated to gene, cell and drug therapies. Its main objective is to facilitate and accelerate new drug and new therapies creation and development thanks to the gathering on a single geographical site of technological skills, medical skills and industrial network. The general objective of this research is to design, anticipate and improve the management of such a pole of competence, especially in terms of costs and creation of values (such as scientific, environmental, social or ethical values). Our systemic approach, called SCOS'D (Systemics for Complex Organisational Systems' Design), is used to design this new organisational system to meet in the best possible way the expectations of all stakeholders. This paper presents the different possible perspectives of the proposed method too, for example performance measurement and control, quality management or costs/values balance, through the tool SCOS'C² (Systemics for Complex Organisational Systems' Command and Control)

Early design decision support with system dynamics approaches - Example of telehealth integration in the healthcare system

International audienceThe purpose of this article is to use System Dynamics approaches for early design decision support. Telehealth is proposed in many articles as one of the possibilities to answer the challenges of keeping and reinforcing the goodness and fairness of the healthcare systems. But very few studies focus on predicting telehealth integration in the current healthcare system. The model proposed in this paper simulates several scenarios of telehealth integration in order to reduce healthcare cost and save valuable medical time. It also highlights the main factors that have the most influence on the results and provides help for healthcare managers to choose between different strategies and healthcare policies

Intrusion and extrusion of water in hydrophobic mesopores

We present experimental and theoretical results on intrusion-extrusion cycles of water in hydrophobic mesoporous materials, characterized by independent cylindrical pores. The intrusion, which takes place above the bulk saturation pressure, can be well described using a macroscopic capillary model. Once the material is saturated with water, extrusion takes place upon reduction of the externally applied pressure; Our results for the extrusion pressure can only be understood by assuming that the limiting extrusion mechanism is the nucleation of a vapour bubble inside the pores. A comparison of calculated and experimental nucleation pressures shows that a proper inclusion of line tension effects is necessary to account for the observed values of nucleation barriers. Negative line tensions of order $10^{-11} \mathrm{J.m}^{-1}$ are found for our system, in reasonable agreement with other experimental estimates of this quantity

Connecting diffusion and dynamical heterogeneities in actively deformed amorphous systems

We present an extensive numerical study of dynamical heterogeneities and their influence on diffusion in an athermal mesoscopic model for actively deformed amorphous solids. At low strain rates the stress dynamics are governed by cooperative regions of plastic events. On the basis of scaling arguments as well as an extensive numerical study of an athermal elasto-plastic model, we show that there is a direct link between the self-diffusion coefficient and the size of cooperative regions at low strain rates. Both depend strongly on rate and on system size. A measure of the mean square displacement of passive tracers in deformed amorphous media thus gives information about the microscopic rheology, such as the geometry of the cooperative regions and their scaling with strain rate and system size