Protéger la concurrence ou protéger les concurrents ? L'affaire Intel en perspective

International audienceWhile the European Commission have imposed a huge fine on Intel (almost €1.07 billion) for having abused of its dominance on the microprocessor's industry, US antitrust authorities seem much more reluctant to settle suits brought by AMD - the Intel's sole serious competitor on this market - in the same way. Our present purpose is to analyze the reasons likely to explain those transatlantic divergences in competition policies relative to fidelity rebates granted by dominant undertakings.La condamnation d'Intel, leader mondial des microprocesseurs, pour abus de position dominante par la Commission européenne le 13 mai 2009 met en exergue la question des possibilités d'éviction de firmes concurrentes par des politiques de remises de fidélité menées par un opérateur dominant. S'il apparaît comme tout à fait possible au point de vue théorique d'exclure du marché, au travers d'une telle politique commerciale, des concurrents au moins aussi efficaces que l'entreprise dominante, il n'en demeure pas moins que le cas Intel témoigne de fortes divergences entre les différentes autorités nationales de la concurrence quant au traitement de telles affaires. En effet, si Intel a d'ores-et-déjà fait l'objet de condamnations au Japon, en Corée du Sud et maintenant par l'Union européenne, la situation est bien moins claire dans le cas américain. L'absence de réaction de la division Antitrust du Département de la Justice s'explique en fait par la prédominance d'une conception des plus précautionneuses quant au traitement des pratiques unilatérales des entreprises dominantes. Il s'agit donc dans cet article d'analyser les faits reprochés à Intel et de s'attacher à expliquer les fondements théoriques des différences de réactions des autorités de la concurrence de part et d'autre de l'Atlantique

Using the International Monitoring System infrasound network to study gravity waves

International audienceThe infrasound network of the International Monitoring System (IMS) has been designed for the detection of atmospheric pressure fluctuations produced in the [0.02 Hz-4 Hz] frequency range. However, the majority of the measuring chains used in this network also record pressure fluctuations at lower frequencies. The objective of this paper is to demonstrate the accuracy of IMS pressure measurements in the gravity wave band, whose period usually ranges from a few minutes to 24 hours. Application examples such as the monitoring of worldwide gravity wave time-spectra and the characterization of surface pressure fluctuations produced by atmospheric tides are presented. This study opens the way to the analysis of gravity waves using IMS data, which constitute a unique and accurate set of pressure measurements

Evaluation de la méthode SAS sur un rotor de compresseur haute-pression

International audienceThe main design objectives of a high pressure compressor are the aerodynamic efficiency and the operating range (e.g. the surge margin). Those quantities are impacted by secondary and leakage flows occurring in the blade passage such as corner separation or stall and tip leakage flows. The turbulence modeling influences strongly the prediction of the overall performances. The aims of the present study were (i) the validation of the combination of the SAS approach with the DRSM turbulence model by comparison to experimental data, especially to laser measurements in the tip of a rotor of a high pressure compressor and (ii) the discussion of the flow prediction improvements with respect to turbulence approaches classically used in CFD and industry: URANS simulations and standard SAS simulation i.e. combined with SST turbulence model. The SAS results are compared to experimental data and to URANS results (SST and DRSM). Only the simulations with IGV wakes predict the velocity fluctuations near tip gap, from the leading edge. Concerning the time-averaged performances, the stagnation pressure losses are slightly overestimated by SAS, especially with DRSM model. This is due to an amplification of the hub corner separation. Moreover, the isentropic efficiency is very sensitive to the SAS approach and to the turbulence model. The spectral analysis shows that the prediction of the amplitude and frequencies of the power spectral density of static pressure is improved using the SAS approach instead of URANS one. The SAS approach leads to PSD similar to ZDES, especially with the DRSM model. Thus, the SAS-DRSM is able to well predict the tip leakage flow with the fine mesh. Nevertheless, this approach amplifies the hub corner separation leading to a strong underestimation of overall performances

RANS Simulation of Laminar-Turbulent Transition in Separation Bubbles on Airfoils

International audiencePredicting the location of laminar-turbulent transition, and modelling the transition region inside a separation bubble are two related questions presently limiting the performance of flow simulations. Considering these questions requires both an understanding of the underlying physics and a number of improvements of the available numerical tools. Several airfoils presenting short and long laminar bubbles are considered, trying to define a common approach with an internal prediction of laminar-turbulent transition. Comparisons to existing measurements and current predictions will be presented. Two methods for transition prediction are used with the same elsA numerical platform, transition criteria and the Menter-Langtry approach

Felletin

Identifiant de l'opération archéologique : 122331 Date de l'opération : 2005 (PI) Dans le cadre de « l’inventaire général du patrimoine architectural et mobilier de la commune de Felletin » engagé en 2002, la ville de Felletin, le conseil général de la Creuse et la DRAC du Limousin pour l’Etat ont souhaité la réalisation d'une étude historique et documentaire de la ville, en orientant les problématiques sur la question des origines et de la genèse de la ville médiévale de Felletin qui devait ..

Divergences transatlantiques en matière d’application de la théorie des facilités essentielles aux actifs immatériels

Alors qu’à travers son jugement dans l’affaire Trinko la Cour suprême américaine réitère son rejet de la doctrine des facilités essentielles, la jurisprudence européenne semble opérer un glissement de son application depuis les infrastructures physiques vers les actifs intangibles. Ces deux visions diamétralement opposées répondent de deux conceptions différentes de la concurrence, qu’il s’agisse de l’importance accordée à la structure des marchés ou de l’analyse des incitations à l’innovation. À ce titre, l’affaire Microsoft constitue un exemple évocateur des divergences transatlantiques en matière de politiques de concurrence. Cet araticle expose les fondements des décisions prises par les autorités de concurrence européenne et américaine dans les affaires relatives à des refus de cession de licence et propose un éclairage à travers les doctrines économiques dominantes de part et d’autre de l’Atlantique.While the US Supreme Court, throughout its judgment in Trinko, rejects the essential facilities doctrine, in the European Union it is not only accepted but even extended to intangible assets. Two contradictory conceptions of competition prevail on either sides of the Atlantic, with regard to the importance of market structures and the question of incentives to innovate. As a pertinent illustration of these different conceptions of competition policies, the Microsoft case seems very eloquent. This article sets out the grounds of the US and EU antitrust authorities’ decisions in regard to refusal to deal litigations. In this way, we will spotlight the dominant economic doctrines on both sides of the Atlantic

Étude expérimentale et modélisation de l'écoulement de jeu d'une aube fixe isolée

International audienceThe tip-leakage flow has detrimental effects on the performance of compressors. In this paper the effects of gap height and incoming casing boundary layer thickness are analyzed. Velocity and total pressure measurements are carried out in a plane behind the trailing edge of an isolated fixed blade. The total pressure loss is decomposed in a vortex loss and a wake loss. It appears that the increase of total pressure losses with the gap height comes essentially from the vortex part. This observation motivated the development of a model based on an analogy with a jet in crossflow to estimate the tip-leakage vortex circulation. The predictions of this model are consistent with the experimental data for gaps smaller than 4 % of chord

Evaluation of Zonal Detached Eddy Simulation k-ω and Scale Adaptive Simulation methods on a realistic rotor of a high-pressure compressor

In order to improve turbomachinery performances it is necessary to correctly predict secondary and transitional flows inherent to this confined environment. Secondary flows can cause additional loss and operating domain reduction. For example, tip-leakage vortex flow or corner separation flow on high pressure compressor blades lead to total pressure loss limiting turbomachinery efficiency and favoring emergence of hazardous axial instability (surge). Secondary flows often exhibit strong fluctuating behaviors and flow separations which make their prediction quite challenging, often found inaccurate with current turbulence modeling tools used during design process. One reason lies in the error on turbulent fluctuation predictions when they are entirely modeled by statistical averaging (RANS - Reynolds Average Navier-Stokes). However, more accurate methods such as Large Eddy Simulations (LES) are difficult to use at high Reynolds number due to excessive computation, treatment and storage costs. A trade-off can be found in hybrid RANS/LES methods such as ZDES (Zonal Detached Eddy Simulation) method developed at ONERA. Through the main operating mode of ZDES method, boundary layers are treated by RANS modeling on their whole thickness to avoid near-wall excessive cost of LES method which is only used away of the walls. The interface between those two sub-methods is continuous. Its RANS sub-method is based on SA turbulence model. As demonstrated by W. Riéra (Ph.D. thesis, Evaluation of the ZDES method on an axial compressor: analysis of the effects of upstream wake and throttle on the tip-leakage flow, Ecole Centrale de Lyon, 2014) the SA turbulence model used in the RANS sub-method of the current ZDES method makes difficult to predict turbomachinery flows at limit operating range because of its poor behavior near numerical surge line. A major reason is that RANS SA model tends to predict too massive or simply false flow separations, which is critical for such flows with corner flow separation. A suggested remedy is to re-based the ZDES method on a k-? Menter turbulence model which present better behavior regarding progressive flow separation prediction. Several ZDES k-? Menter method formulations have been assessed on three academic cases (a mixing layer flow, a backward facing step flow and a circular cylinder flow at Re = 3900, AIAA Aviation 2017). One of these formulations has been selected based on its capability (i) to allow the emergence and the correct development of Kelvin-Helmholtz instabilities and (ii) to ensure that boundary layers are treated by RANS modeling in their entire thickness. Alternatively to hybrid RANS/LES methods, upgraded URANS approaches are interesting tools for resolving a variable fraction of the larger scales of turbulent motions, allowing a better representation of unsteady flows than URANS methods. Among them, the Scale Adaptive Simulation (SAS) approach of has been implemented in ONERA's elsA solver with an improvement dealing with the development of instabilities within mixing layers. This study focuses on the validation of the selected ZDES k-? Menter formulation and the SAS approach on the same configuration as W. Riéra ZDES SA simulation i.e. a flow simulation of a realistic rotor of a high-pressure compressor with incoming stator wakes. Simulation is carried out on the same mesh and numerical framework as W. Riéra ones for appropriate comparison with their ZDES SA results and with experimental data