219 research outputs found
Rotorcraft Flight Envelope Protection by Model Predictive Control
No full textA novel flight envelope protection method is presented. The approach is based on a model predictive receding horizon formulation, which computes at each instant in time the future extremal control inputs that would lead the vehicle to ride the flight envelope boundary without ever exceeding it. The extremal inputs are then used for pilot cueing. The calculation of the extremal inputs is based on the constrained optimization of a quadratic figure of merit for a reduced-order linear parameter varying model of the vehicle. The model accounts for the cross-couplings among the inputs that characterize the flight mechanics of rotorcraft vehicles and spans the entire flight envelope of interest by piecewise linear interpolation of given trim points. The approach leads to a convex optimization problem, which can be computed very efficiently in real time using a deterministic number of operations. A heuristic modification to the limits of the critical parameters, driven by a reduced-order nonlinear model of the vehicle, is used for online solution adaptation against possible model mismatch. The new approach is demonstrated by numerical simulation of multiple complex pilot-in-the-loop aggressive maneuvers
A New Concept to Mitigate Loads for Wind Turbines Based on a Passive Flap
No full textThis paper considers the preliminary investigation of a passive flap for the mitigation of loads on wind turbines. The flap moves passively in response to blade vibrations, opposing them, thereby yielding an attenuation of loads. In comparison to active flaps, this solution has the advantage of not requiring sensors nor actuators, resulting in a particularly simple implementation, with potential benefits in manufacturing and maintenance costs. The paper first describes the concept of the novel passive flap, highlighting its main characteristics. A proof of concept of the new idea is then given by a simulation study conducted with the combination of a sectional model of the flap and a multibody model of the rest of the machine. Results, obtained for a 10MW wind turbine, indicate the ability of the passive flap in attenuating blade vibrations in a significant frequency range, which in turn yield a reduced fatigue damage to the structure without noticeable effects in terms of power production
Quality principles for cultural Web sites: a Handbook
No full textprinted and on-line versions, co-author with Eelco Bruinsma, Christophe Dessaux, Ciaran Clissman, Jean-Pierre Dalbéra, David Dawson, Isabelle Dujacquier, Axel Ermert, Pierluigi Feliciati, Fedora Filippi, Muriel Foulonneau,
Antonella Fresa, Monika Hagedorn-Saupe, Annette Kelly, Brian Kelly, Daniel Malbert, Andrea Mulrenin, Stefan Rhode-Enslin, Marius Snyders, Gert Van Tittelboom, Frank von Hage
Ultimate and fatigue load mitigation by an inertial-driven passive flap, using a geometrically exact multibody formulation
No full textThe paper characterizes the performance of a passive flap concept when applied to a modern very large conceptual wind turbine. The passive flap responds automatically to blade and/or tower vibrations, inducing a change of camber that opposes dynamic loads on the wind turbine. This is obtained in a purely passive manner, without the need for actuators or sensors. The present study is based on a detailed, geometrically exact multibody formulation of the device, which is able to capture all kinematic and structural dynamic effects of this inertia-driven device. The present modeling of the passive device improves on previous studies conducted with simplified models. Results show a significant ability in the reduction of both fatigue and ultimate loads, including the case of flap-specific fault scenarios. Solutions for limiting losses in energy yield caused by non-null average flap rotations in the partial load region are also investigated. The present analysis motivates further studies aimed at reaping the benefits of load alleviation enabled by the passive flap, for example by designing a new enlarged rotor at similar key loads on the rest of the machine
Load mitigation for wind turbines by a passive aeroelastic device
No full textThis paper conducts a preliminary investigation of a novel passive concept for the mitigation of loads on wind turbines. The device, which can be implemented as a flap or a pitching blade tip, moves passively in response to blade vibrations, opposing them, thereby yielding an attenuation of loads. In comparison to active load mitigation devices, such as active flaps, this solution has the advantage of not requiring sensors nor actuators, resulting in a particularly simple implementation, with potential benefits in manufacturing and maintenance costs, as well as in reliability and availability.The paper first describes the novel passive device, here implemented by means of a flap, highlighting its main characteristics. A proof of concept of the new idea is then given by a simulation study conducted with the combination of a sectional model of the flap and an aeroservoelastic multibody model of the rest of the machine. Results, obtained for a 10. MW wind turbine, indicate the ability of the passive flap in attenuating blade vibrations in a significant frequency range, which in turn yield a reduced fatigue damage to the structure without noticeable effects in terms of power production and ultimate loads
Cheating, inequality aversion, and appealing to social norms
No full textWe conduct a field experiment involving 143, 9-years old children in their classrooms. Children are requested to flip a coin in private and receive a big or a small prize depending on the outcome they report. Comparing the actual and theoretical distribution of reported wins, we find evidence of cheating at the aggregate level. By using behavioral data gathered on previous and subsequent meetings with the same children, we are able to explore the relationship between cheating behavior, other regarding preferences, and the tendency to appeal to social norms in judging unfair behaviors. Children who are classified as concerned about inequality are less likely to cheat. Similarly, children who are more likely to appeal to social norms in judging unfair behaviors are also less likely to cheat. We find no significant relationship between inequality concern and social norms sensitivity, suggesting that these mechanisms work differently interacting with children moral behavior. (C) 2019 Elsevier B.V. All rights reserved
Erosion de la nature, stratification de l'humain. Tournant ontologique et écologie sémiotique
No full textThe article “Érosion de la nature, stratification de l’humain: Tournant ontologique et écologie sémiotique” by Pierluigi Basso Fossali explores the interplay between ecological thought and semiotics, emphasizing the ontological challenges posed by the relationship between nature and culture. The author critiques the oversimplification of nature as a static regulatory principle, advocating instead for a dynamic semiotic ecology that acknowledges the interdependence of cultures, environments, and symbolic systems. The text highlights the necessity of rethinking environmental discourse through a multi-layered perspective that transcends traditional dichotomies, such as nature versus culture, while embracing the epistemological contributions of diverse civilizations. By integrating the notions of resistance, translation, and intersubjectivity, the article argues for a pluralistic understanding of ecological frameworks as both cultural constructs and practical paradigms for addressing global environmental challenges
Playing with autism. Encountering Simona Concaro by her music. Vol. 1.1
No full textPlaying with Autism contains twenty-four original pieces for piano, recorded and carefully transcribed in current music notation by Pierluigi Politi and Hanna Shybayeva. Simona Concaro, the author, is a young woman suffering of low-functioning autism. She lives in Cascina Rossago, a farm-community, designed to meet the needs of people with autism, in Oltrepo pavese (Italy).
Since she was three, Simona Concaro has created original compositions on piano, instrument she learned by herself, refusing any kind of musical education. In everyday life, Simona does not use verbal language and has low autonomy. Her music, on the contrary, contains interesting features – melodic, rhythmic and harmonic –, even in the presence of some iterative elements, typical of the autistic spectrum
Inertial and aerodynamic tuning of passive devices for load alleviation on wind turbines
No full textThis paper describes tuning concepts for passive devices aimed at load alleviation in wind turbines. Two types of tuning are considered: inertial and aerodynamic. The first concept is illustrated with reference to a passive flap, while the second with reference to a passive tip. In both cases, the goal is to reduce loads with devices that are as simple as possible, and do not require sensors nor actuators. The main features and critical issues of each concept are highlighted and illustrated with reference to a large conceptual 10 MW wind turbine
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