363 research outputs found
Influence of Process and Material Parameters on Impact Response in Composite Structure: Methodology Using Design of Experiments
Even if the mechanical performances of composite materials give new perspectives for the aircraft and space design, the variability of their behavior, linked to the presence of initial microscopic defects or led in service, constitute however a still important brake in their development. As regards particularly the response to fatigue loads or ageing, the behavior of these materials is affected by several sources of uncertainties, notably on the nature of the physical mechanisms of degradation, which are translated by a strong dispersion in life time.
In aerospace industry, low energy impact phenomenon is not well known concerning composite materials and composite structures. Many manufacturers use important safety factors to design structures. The aim of this work is to define the most predominant parameters which permit a good response of damage using experiences plans. The differences of these parameters by using Resin Transfer Molding (RTM) or Liquid Resin Infusion (LRI) process than prepreg one is also studied in this work
Robust algorithm for calibration of robotic manipulator model
The paper focuses on the robust identification of geometrical and elastostatic parameters of robotic manipulator. The main attention is paid to the efficiency improvement of the identification algorithm. To increase the identification accuracy, it is proposed to apply the weighted least square technique that employs a new algorithm for assigning of the weighting coefficients. The latter allows taking into account variation of the measurement system precision in different directions and throughout the robot workspace. The advantages of the proposed approach are illustrated by an application example that deals with the elasto-static calibration of industrial robot.AN
Z. David Zuwiyya (Ă©d.), A Companion to Alexander Literature in the Middle Ages
SpĂ©cialiste du Roman alexandrin, Z. D. Zuwiyya coordonne ici un ouvrage qui se propose dâinventorier richement la postĂ©rioritĂ© des rĂ©cits traitant de lâĂ©popĂ©e dâAlexandre le Grand dans la littĂ©rature mĂ©diĂ©vale â cinquante-cinq ans aprĂšs G. Cary â en faisant ressortir la gĂ©nĂ©alogie, ascendante comme descendante, de ces traditions. Eu Ă©gard Ă la nature composite de ce vaste vadĂ©mĂ©cum, nous maintiendrons dans les lignes qui suivent sa structure encyclopĂ©dique. R. Stoneman examine les sources pri..
La traduction princeps de lâExplication sur le temple divin de SymĂ©on de Thessalonique par Pontanus en 1603
Dans notre sĂ©rie de confĂ©rences pour lâannĂ©e 2016-2017, il sâest agi dâapprofondir et dâĂ©tudier les conditions qui ont permis Ă lâĆuvre de SymĂ©on de Thessalonique dâĂȘtre lue, Ă©ditĂ©e et traduite en Occident avant lâĂ©dition DosithĂ©e
LâĂ©dition DosithĂ©e (1683) des Opera omnia de SymĂ©on de Thessalonique
SymĂ©on (â  1429), archevĂȘque de Thessalonique durant la dĂ©cennie qui prĂ©cĂ©da la prise dĂ©finitive de cette ville par les Ottomans en 1430, fut lâun des auteurs ecclĂ©siastiques les plus prolixes et les plus lus de lâĂglise byzantine du xve siĂšcle. DĂšs avant la chute de Thessalonique, un vĂ©ritable corpus de ses Ćuvres avait dĂ©jĂ commencĂ© de se diffuser, comme en tĂ©moigne le nombre considĂ©rable de manuscrits qui le mirent en circulation du xve au xviiie siĂšcle, tant en Orient quâen Occident. Les r..
LâĂ©dition DosithĂ©e (1683) des Opera omnia de SymĂ©on de Thessalonique
SymĂ©on (â  1429), archevĂȘque de Thessalonique durant la dĂ©cennie qui prĂ©cĂ©da la prise dĂ©finitive de cette ville par les Ottomans en 1430, fut lâun des auteurs ecclĂ©siastiques les plus prolixes et les plus lus de lâĂglise byzantine du xve siĂšcle. DĂšs avant la chute de Thessalonique, un vĂ©ritable corpus de ses Ćuvres avait dĂ©jĂ commencĂ© de se diffuser, comme en tĂ©moigne le nombre considĂ©rable de manuscrits qui le mirent en circulation du xve au xviiie siĂšcle, tant en Orient quâen Occident. Les r..
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Dans le ventre de lâhistoire: Sindbad le marin ou la satire du glouton?
Le cycle des sept voyages de Sindbad le marin comprend un grand nombre dâactes diĂ©gĂ©tiques relevant du manger. Plus profondĂ©ment, nous soutenons ici que la progression mĂȘme de chaque pĂ©ripĂ©tie sâappuie sur une forme de repas. Ă bien y regarder, les intrigues, plus ou moins complexes, comportent toutes une ou plusieurs scĂšnes dans lesquelles se nourrir dĂ©termine la suite des Ă©vĂ©nements. Nous croyons que les narrĂšmes mobilisĂ©s servent un projet qui ressortit Ă lâadab : montrer jusquâĂ quelles extrĂ©mitĂ©s lâaccumulation pousse les hommes. Le motif alimentaire au cĆur de ce dispositif relĂšve alors de la mĂ©taphore, celle du glouton.
The story cycle of Sindbad the Sailorâs seven travelogues contains many diegetic acts related to eating. I will argue that on each journey, the narrative relies on the form of a meal. Furthermore, on closer inspection, the plots, whether complex or not, all contain one or more scenes in which feeding determines the sequence of events. I contend that the underlying narremes serve a purpose pertaining to the axiological adab system: to show to what extremes accumulation can drive people. From this perspective, the food motif at the heart of this literary device falls under the metaphor of a glutton
Comparaison entre quatre solutions pour échanger de l'énergie entre systÚmes de forte capacité de stockage
International audienceL'électrification de systÚmes toujours plus puissants est habituellement corrélée à de plus grands besoins de fiabilité, continuité de service et échanges d'énergie entre sources. Dans le domaine des systÚmes de stockage électrochimique d'énergie, ces besoins sont souvent satisfaits en parallélisant des batteries. La déconnexion de deux batteries en parallÚle est un processus simple et bien maßtrisé. En revanche, la connexion est un processus bien plus long et compliqué qui requiÚre de l'électronique de puissance adaptée car cela revient à connecter en parallÚle deux sources de tension. Basé sur un cas concret d'application et grùce à des simulations, cet article propose une comparaison entre quatre solutions pour échanger de l'énergie entre systÚmes batterie lithium-ion et maitriser la connexion en parallÚle de ceux-ci
Random integrals and correctors in homogenization
International audienceThis paper concerns the homogenization of a one-dimensional elliptic equation with oscillatory random coefficients. It is well-known that the random solution to the elliptic equation converges to the solution of an effective medium elliptic equation in the limit of a vanishing correlation length in the random medium. It is also well-known that the corrector to homogenization, i.e., the difference between the random solution and the homogenized solution, converges in distribution to a Gaussian process when the correlations in the random medium are sufficiently short-range. Moreover, the limiting process may be written as a stochastic integral with respect to standard Brownian motion. We generalize the result to a large class of processes with long-range correlations. In this setting, the corrector also converges to a Gaussian random process, which has an interpretation as a stochastic integral with respect to fractional Brownian motion. Moreover, we show that the longer the range of the correlations, the larger is the amplitude of the corrector. Derivations are based on a careful analysis of random oscillatory integrals of processes with long-range correlations. We also make use of the explicit expressions for the solutions to the one-dimensional elliptic equation
Intensification of heat-transfer and mixing in heat exchanger-reactors by artificially generated streamwise vortices
International audienceCompact heat exchangers are well known for their ability to transfer a large amount of heat while retaining low volume and weight. The purpose of this paper is to study the potential of using this device as a mixer as well as a chemical reactor, generally called a multifunctional heat exchanger (MHE). Indeed, the question arises: can these geometries combine heat transfer and mixing in the same device? Such a technology would offer many potential advantages, such as better reaction control (through the thermal aspect [S. Ferrouillat, P. Tochon, H. Peerhossaini, D. Della Valle, Open-loop thermal control of exothermal chemical reactions in multifunctional heat exchangers, Int. J. Heat Mass Transfer, in press]), improved selectivity (through intensified mixing, more isothermal operation and shorter residence time, and sharper residence time distribution (RTD)), byproduct reduction, and enhanced safety.Several geometries of compact heat exchanger based on turbulence generation are available. This paper focuses on one type: vortex generators. The main objective is to contribute to the determination of turbulent flow inside various geometries by computational fluid dynamics methods. These enhanced industrial geometries are studied in terms of their thermal-hydraulic performance and macro-/micro-mixing ability [S. Ferrouillat, P. Tochon, H. Peerhossaini, Micromixing enhancement by turbulence: application to multifunctional heat exchangers, Chem. Eng. Process., in press]. The longitudinal vortices they generate in a channel flow turn the flow perpendicular to the main flow direction and enhance mixing between the fluid close to the fin and that in the middle of the channel. Two kinds of vortex generators are considered: a delta winglet pair and a rectangular winglet pair. For both, good agreement is obtained between numerical results and data in the literature. The vortex generator concept is found to be very efficient in terms of heat-transfer enhancement and macro-mixing. Nevertheless, the micro-mixing level is poor due to strong inhomogeneities: the vortex generator must be used as a heat-transfer enhancement device or as a static mixer for macro- and meso-mixing
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