Role of dynamic Jahn-Teller distortions in Na2C60 and Na2CsC60 studied by NMR

Through 13C NMR spin lattice relaxation (T1) measurements in cubic Na2C60, we detect a gap in its electronic excitations, similar to that observed in tetragonal A4C60. This establishes that Jahn-Teller distortions (JTD) and strong electronic correlations must be considered to understand the behaviour of even electron systems, regardless of the structure. Furthermore, in metallic Na2CsC60, a similar contribution to T1 is also detected for 13C and 133Cs NMR, implying the occurence of excitations typical of JT distorted C60^{2-} (or equivalently C60^{4-}). This supports the idea that dynamic JTD can induce attractive electronic interactions in odd electron systems.Comment: 3 figure

Reducing Uncertainties in a Wind-Tunnel Experiment using Bayesian Updating

We perform a fully stochastic analysis of an experiment in aerodynamics. Given estimated uncertainties on the principle input parameters of the experiment, including uncertainties on the shape of the model, we apply uncertainty propagation methods to a suitable CFD model of the experimental setup. Thereby we predict the stochastic response of the measurements due to the experimental uncertainties. To reduce the variance of these uncertainties a Bayesian updating technique is employed in which the uncertain parameters are treated as calibration parameters, with priors taken as the original uncertainty estimates. Imprecise measurements of aerodynamic forces are used as observational data. Motivation and a concrete application come from a wind-tunnel experiment whose parameters and model geometry have substantial uncertainty. In this case the uncertainty was a consequence of a poorly constructed model in the pre-measurement phase. These methodological uncertainties lead to substantial uncertainties in the measurement of forces. Imprecise geometry measurements from multiple sources are used to create an improved stochastic model of the geometry. Calibration against lift and moment data then gives us estimates of the remaining parameters. The effectiveness of the procedure is demonstrated by prediction of drag with uncertainty

Analysis of Multi-Element Airfoil High Lift Improvement by Efficient Upper Surface Suction

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Conceptual study of a morphing winglet based on unsymmetrical stiffness

Morphing technology has the potential to increase aircraft performance. Among the morphing technologies, the morphing winglet is a promising solution due to its small size and large effect on the aerodynamics. Morphing winglets have to carry the spanwise aerodynamic loads, with low weight and small size. This makes the design of a reliable morphing structure of great importance to realize a morphing winglet.In this paper, a novel compliant structure is proposed based on the concept of unsymmetrical stiffness. The morphing winglet has to change its dihedral angle, and its stiffness has to be large enough to carry loads. While increasing the total stiffness, the allocation of the stiffness can be unsymmetrical, introducing deformation under a linear actuation force. If the total stiffness and its asymmetry are properly designed, the final deformation under both aerodynamic loads and actuation force can be optimized. The current study uses different composite layups of round corrugation structures to provide the stiffness asymmetry. A simplified model is developed to estimate the induced deformation and required actuation force. The deformation limit of the structure is also predicted using detailed finite element analysis.To demonstrate the application of the morphing structure, the baseline design of a regional twin turboprop airliner is generated. A worm and rack actuation mechanism is also designed. For performance analysis, the weight due to the morphing winglet and its actuation system is estimated. The influence of retrofitting the baseline design is investigated to obtain a trade-off design for the morphing structure.From the conceptual study, the simplified approach provides the basic properties of the morphing structure to retrofit the baseline aircraft, which highlights the feasibility of this novel concept although further study is still needed for its detailed design and analysis

Advanced turboprop multidisciplinary design and optimization within agile project

The present paper deals with the design, analysis and optimization of a 90 passengers turboprop aircraft with a design range of 1200 nautical miles and a cruise Mach number equal to 0.56. The prescribed aircraft is one of the use cases of the AGILE European project, aiming to provide a 3rd generation of multidisciplinary design and optimization chain, following the collaborative and remote aircraft design paradigm, through an heterogenous team of experts. The multidisciplinary aircraft design analysis is set-up involving tools provided by AGILE partners distributed worldwide and run locally from partners side. A complete design of experiment, focused on wing planform variables, is performed to build response surfaces suitable for optimization purposes. The goal of the optimization is the direct operating cost, subject to wing design variables and top-level aircraft requirements

N+3 Aircraft Concept Designs and Trade Studies

Appendices A to F present the theory behind the TASOPT methodology and code. Appendix A describes the bulk of the formulation, while Appendices B to F develop the major sub-models for the engine, fuselage drag, BLI accounting, etc

Moderate exercise may attenuate some aspects of immunosenescence

BACKGROUND: Immunosenescence is related to the deterioration of many immune functions, which may be manifested in increased susceptibility to infection, cancer, and autoimmunity. Lifestyle factors, such as diet or physical activity, may influence the senescence of the immune system. It is widely accepted that moderate physical activity may cause beneficial effects for physical and psychological health as well as for the immune system activity in aged people. METHODS: Thirty elderly women aged 62 to 86 were subjected to a two-years authorized physical activity program. Peripheral blood lymphocytes distribution and the production of cytokines involved in the immune response development and regulation (IL-2, IL-4 and IFN-γ) were investigated. The same parameters were evaluated in two control groups of women: a sedentary group of 12 elderly women selected for the second round of the physical activity program and in a group of 20 sedentary young women. Flow cytometry methods were used for the examination of surface markers on peripheral blood lymphocytes and intracellular cytokines expression. RESULTS: The distribution of the main lymphocytes subpopulations in the peripheral blood of elderly women did not show changes after long-term moderate physical training. The percentage of lymphocytes expressing intracellular IL-2 was higher in the group of women attending 2-years physical activity program than in the control group of elderly sedentary women, and it was similar to the value estimated in the group of young sedentary women. There was no difference in the intracellular expression of IL-4 and IFN-γ between the active and elderly sedentary women. CONCLUSIONS: Our results suggest that moderate, long-term physical activity in elderly women may increase the production of IL-2, an important regulator of the immune response. This may help ameliorate immunosenescence in these women