Gunter Barrie, Rowlands Ian & Nicholas David : The Google Generation. Are ICT innovations changing information-seeking behaviour?Connaway Lynn S. & Dickey Timothy J. : The Digital Information Seeker. Report of Findings from Selected OCLC, RIN and JISC User Behaviour Projects

Le succès de l’information scientifique en ligne est fulgurant. Depuis le début des années 90, la nouvelle offre documentaire a transformé l’ensemble de la chaîne de valeur de l’édition scientifique. Cette transformation a été accompagnée par une interrogation sur les pratiques des chercheurs. Un corpus de plus en plus riche d’études et de recherches a tenté de mesurer et de comprendre le comportement des chercheurs, leur façon de chercher l’information scientifique sur Internet, l’appropriat..

Experimental study of the flight envelope and research of safety requirements for hang-gliders

The flight mechanic computations were computed, providing both the flight envelopes with all sorts of limits and a fairly precise idea of the influence of several parameters, such as pilot's weight, wing settings, aeroelasticity, etc... The particular problem of luffing dives was thoroughly analyzed, and two kinds of causes were exhibited in both the rules of luffing and aeroelastic effects. The general analysis of longitudinal stability showed a strong link with fabric tension, as expected through Nielsen's and Twaites' theory. Fabric tension strongly depending upon aeroelasticity, that parameter was found to be the most effective design one for positive stability. Lateral stability was found to be very similar in all gliders except perhaps the cylindro-conical. The loss of stability happens in roll at low angle of attack, whereas it happens in yaw at high angle. Turning performance was a bit suprising, with a common maximum value of approximately 55 deg of bank angle for a steady turn

Differential continuum damage mechanics models for creep and fatigue of unidirectional metal matrix composites

Three multiaxial isothermal continuum damage mechanics models for creep, fatigue, and creep/fatigue interaction of a unidirectional metal matrix composite volume element are presented, only one of which will be discussed in depth. Each model is phenomenological and stress based, with varying degrees of complexity to accurately predict the initiation and propagation of intergranular and transgranular defects over a wide range of loading conditions. The development of these models is founded on the definition of an initially transversely isotropic fatigue limit surface, static fracture surface, normalized stress amplitude function and isochronous creep damage failure surface, from which both fatigue and creep damage evolutionary laws can be obtained. The anisotropy of each model is defined through physically meaningful invariants reflecting the local stress and material orientation. All three transversely isotropic models have been shown, when taken to their isotropic limit, to directly simplify to previously developed and validated creep and fatigue continuum damage theories. Results of a nondimensional parametric study illustrate (1) the flexibility of the present formulation when attempting to characterize a large class of composite materials, and (2) its ability to predict anticipated qualitative trends in the fatigue behavior of unidirectional metal matrix composites. Additionally, the potential for the inclusion of various micromechanical effects (e.g., fiber/matrix bond strength, fiber volume fraction, etc.), into the phenomenological anisotropic parameters is noted, as well as a detailed discussion regarding the necessary exploratory and characterization experiments needed to utilize the featured damage theories

Experimental and Computational Icing Simulation for Large Swept Wings

The overall goal of this research was to improve the experimental and computational simulation capability for icing on large swept wings typical of commercial transports. This research included both ice-accretion and aerodynamic studies using the NASA Common Research Model (CRM) as the reference geometry. For this work, a 65-percent-scale version\u2014CRM65\u2014was used as the full-scale baseline airplane geometry. Ice-accretion testing was conducted in the Icing Research Tunnel (IRT) at the NASA Glenn Research Center using three hybrid swept-wing models representing three different stations along the span of the CRM65 wing. The three-dimensional (3D) ice-accretion geometries obtained from these test campaigns were used to evaluate the results of NASA and ONERA 3D icing simulation tools (LEWICE3D and IGLOO3D)

The F2 wind tunnel at Fauga-Mauzac

Details on the French subsonic wind-tunnel F2 that becomes operational on July 1983 are presented. Some of the requirements were: (1) installation of models on any wall of the facility, (2) good observation points due to transparent walls, (3) smooth flow, (4) a laser velocimeter, and (5) easy access and handling. The characteristics include a nonpressurized return circuit, dimensions of 5 x 1.4 x 1.8 m, maximum velocity of 100 m/s and a variable speed fan of 683 kW