103,482 research outputs found
Fourez (G.). — Éduquer : écoles, éthiques, sociétés.
No full textAvanzini Guy. Fourez (G.). — Éduquer : écoles, éthiques, sociétés. . In: Revue française de pédagogie, volume 99, 1992. p. 125
Fourez (G.). — Éduquer : écoles, éthiques, sociétés.
No full textAvanzini Guy. Fourez (G.). — Éduquer : écoles, éthiques, sociétés. . In: Revue française de pédagogie, volume 99, 1992. p. 125
Orbit Transfer Manoeuvres as a Test Benchmark for Comparison Metrics of Evolutionary Algorithms
No full textIn the present paper some metrics for evaluating the performance of evolutionary algorithms are considered. The capabilities of two different optimisation approaches are compared on three test cases, represented by the optimisation of orbital transfer trajectories. The complexity of the problem of ranking stochastic algorithms by means of quantitative indices is analyzed by means of a large sample of runs, so as to derive statistical properties of the indices in order to evaluate their usefulness in understanding the actual algorithm capabilities and their possible intrinsic limitations in providing reliable information
Lanosheere (G. de). — Introduction à la recherche en éducation, 3e éd.
No full textAvanzini Guy. Lanosheere (G. de). — Introduction à la recherche en éducation, 3e éd.. In: Revue française de pédagogie, volume 17, 1971. pp. 57-58
Psychologie pédagogique. Tome 1: les transformations de l'enfance, G. Cruchon. 1966.
No full textAvanzini Guy. Psychologie pédagogique. Tome 1: les transformations de l'enfance, G. Cruchon. 1966.. In: Revue française de pédagogie, volume 1, 1967. pp. 41-43
Bruliard (L.), et Schlemminger (G.). — Le mouvement Freinet: des origines aux années 1980
No full textAvanzini Guy. Bruliard (L.), et Schlemminger (G.). — Le mouvement Freinet: des origines aux années 1980. In: Revue française de pédagogie, volume 120, 1997. Penser la pédagogie. p. 164
G. Avanzini et M.-J. Thiel, Éduquer à la beauté, éduquer aux valeurs, 1999
No full textWagner Jean-Pierre. G. Avanzini et M.-J. Thiel, Éduquer à la beauté, éduquer aux valeurs, 1999. In: Revue des Sciences Religieuses, tome 74, fascicule 4, 2000. pp. 534-535
Adaptive control of launch vehicles in atmospheric flight
No full textThe research focuses on the development of innovative control techniques for attitude control of a launch vehicle (LV) during the atmospheric flight, and to investigate their possible benefits in terms - for instance - of improved disturbance rejection capability, as well as, a means for reducing the burden of recurrent activities of mission integration and flight program software finalization.
In this respect, a complete nonlinear mathematical model of the launch vehicle dynamics, comprehensive of all relevant aspects for the attitude control problem is first developed. Next, linearized equations of motion are derived under the assumption of small deviations of the vehicle motion from a reference trajectory. The time-invariant linear model is used to synthesize a baseline controller (BC) that features two proportional-derivative (PD) components for attitude and translational motion control, plus filters to phase-stabilize and notch the bending modes by using classical, frequency-based, analysis, and control design techniques.
Among several advanced algorithms referenced in the literature, the Adaptive Augmenting Control (AAC) has been selected and implemented in the LV flight control system in order to retain the functionality and proven record of success of classically designed linear control systems, while consistently and predictably improving their performance and robustness in expanded flight and/or uncertainty parameter envelopes. AAC adjusts the action of a baseline PID-type controller by means of a forward loop gain multiplicative adaptive law that, basically, on-line modulates BC output either to minimize the error with respect to a reference model or to limit undesirable high-frequency response in the control path.
In order to fully exploit the AAC potentiality, an effective and reliable tuning procedure for AAC gains is developed, where a robust design optimization (RDO) problem is formulated, and the goal is to maximize a statistical metric that describes FCS performance measured over a set of LV simulations.
Finally, an analysis of the effects of uncertainties on bending mode characteristics is carried out. Variations of bending mode parameters have a significant and negative impact on AAC performance and, consequently, on LV stability. In this respect, the use of adaptive filters is investigated in order to further improve flight control system robustness. An adaptive notch filter is designed, the parameters of which are updated continuously by an adaptation algorithm that uses the pitch rate sensor output so as to estimate the unknown parameters of the filter and precisely match the actual bending mode frequency
Model predictive control architecture for rotorcraft inverse simulation
No full textA novel inverse simulation scheme is proposed for applications to rotorcraft dynamic models. The algorithm adopts an architecture that closely resembles that of a model predictive control scheme, where the controlled plant is represented by a high-order helicopter model. A fast solution of the inverse simulation step is obtained on the basis of a lower-order, simplified model. The resulting control action is then propagated forward in time using the more complex one. The algorithm compensates for discrepancies between the models by updating initial conditions for the inverse simulation step and introducing a simple guidance scheme in the definition of the tracked output variables. The proposed approach allows for the assessment of handling quality potential on the basis of the most sophisticated model, while keeping model complexity to a minimum for the computationally more demanding inverse simulation algorithm. The reported results, for an articulated blade, single main rotor helicopter model, demonstrate the validity of the approach
Risk assessment in mission planning of uninhabited aerial vehicles
No full textA procedure for evaluating the risk related to the use of unmanned aerial systems over populated areas is proposed. A nominal trajectory, planned for performing a given mission, is represented by means of motion primitives, that is segments and arcs flown in a steady-state condition. The risk of hitting a person on the ground after catastrophic failure is evaluated as a function of vehicle reliability and population density (assumed known), and position of the impact point (which depends on initial conditions at the time of failure and trajectory flown afterwards). In the deterministic case, a lethal area is introduced and the risk at each point on the ground is proportional to the amount of time spent by the point inside the lethal area. Under the assumptions of a ballistic fall, the position of the lethal area with respect to the nominal trajectory depends only on altitude and velocity at the time of failure. When the effect of navigation errors is introduced, impact points are described by a statistical impact footprint, assuming that position and velocity errors at time of failure are normally distributed with known standard deviations. The two approaches are compared for a fictitious, yet realistic, mission scenario
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