Institut supérieur de l'aéronautique et de l'espace

About: Institut supérieur de l'aéronautique et de l'espace is a based out in . It is known for research contribution in the topics: Mars Exploration Program & Seismometer. The organization has 445 authors who have published 644 publications receiving 8049 citations. The organization is also known as: ISAE SUPAERO & National Higher French Institute of Aeronautics and Space.

Predicting the Propagation of Acoustic Waves using Deep Convolutional Neural Networks

Abstract: A novel approach for numerically propagating acoustic waves in two-dimensional quiescent media has been developed through a fully convolutional multi-scale neural network. This data-driven method managed to produce accurate results for long simulation times with a database of Lattice Boltzmann temporal simulations of propagating Gaussian Pulses, even in the case of initial conditions unseen during training time, such as the plane wave configuration or the two initial Gaussian pulses of opposed amplitudes. Two different choices of optimization objectives are compared, resulting in an improved prediction accuracy when adding the spatial gradient difference error to the traditional mean squared error loss function. Further accuracy gains are observed when performing an a posteriori correction on the neural network prediction based on the conservation of acoustic energy, indicating the benefit of including physical information in data-driven methods.

Longitudinal study of a tilt-body vehicle: Modeling, control and stability analysis

Abstract: This work studies a longitudinal high incidence flight envelope dynamic model for use in a convertible tilt-body vehicle designed for indoor/outdoor environments. The model assumptions are chosen so that a singularity-free nonlinear differential equation system is obtained. The model is complex enough to predict wind tunnel experiments yet simple enough to be described by analytical expressions (instead of physically difficult to interpret lookup tables). Wind tunnel measurements took place to identify flying model parameters, validate model and support autopilot design by means of scheduled linear quadratic regulator controller. Finally, controller design is validated by means of stability analysis based on regions of attraction computation via Lyapunov theorems and invariant sets during the entire transition between airplane mode and hover mode.

A practical reachability-based collision avoidance algorithm for sampled-data systems: Application to ground robots

Abstract: We describe a practical collision avoidance algorithm that synthesizes provably safe piecewise constant control laws (compatible with the sampled-data nature of the system) for an experimental platform. Our application is formulated in a pursuer-evader framework in which an automated unmanned vehicle navigates its environment while avoiding a moving obstacle that acts as a malicious agent. Offline, we employ reachability analysis to characterize the evolution of trajectories so as to determine what control inputs can preserve safety over every sampling interval. The moving obstacle is considered unpredictable with nearly no restrictions on its control policies (although we do take into account the physical constraints due to limited dynamical and actuation capacities of both robots). Online, the controller executes computationally inexpensive operations based only on an easy-to-store lookup table. The results of the experiment as well as the proposed algorithm are presented and discussed in detail.

Gemini planet imager observational calibrations III: empirical measurement methods and applications of high-resolution microlens PSFs

Abstract: The newly commissioned Gemini Planet Imager (GPI) combines extreme adaptive optics, an advanced coronagraph, precision wavefront control and a lenslet-based integral field spectrograph (IFS) to measure the spectra of young extrasolar giant planets between 0.9-2.5 μm. Each GPI detector image, when in spectral model, consists of ~37,000 microspectra which are under or critically sampled in the spatial direction. This paper demonstrates how to obtain high-resolution microlens PSFs and discusses their use in enhancing the wavelength calibration, flexure compensation and spectral extraction. This method is generally applicable to any lenslet-based integral field spectrograph including proposed future instrument concepts for space missions.

Asymptotic stability of Webster-Lokshin equation

Abstract: The Webster-Lokshin equation is a partial differential equation considered in this paper. It models the sound velocity in an acoustic domain. The dynamics contains linear fractional derivatives which can admit an infinite dimensional representation of diffusive type. The boundary conditions are described by impedance condition, which can be represented by two finite dimensional systems. Under the physical assumptions, there is a natural energy inequality. However, due to a lack of precompactness of the solutions, the LaSalle invariance principle can not be applied. The asymptotic stability of the system is proved by studying the resolvent equation, and by using the Arendt-Batty stability condition.