Gilles Chardon

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We consider the problem of calibrating a compressed sensing measurement system under the assumption that the decalibration consists in unknown gains on each measure. We focus on blind calibration, using measures performed on a few unknown (but sparse) signals. A naive formulation of this blind calibration problem, using &#x2113;<sub>1</sub> minimization, is(More)
Measuring the Room Impulse Responses within a finite 3D spatial domain can require a very large number of measurements with standard uniform sampling. In this paper, we show that, at low frequencies, this sampling can be done with significantly less measurements, using some modal properties of the room. At a given temporal frequency, a plane wave(More)
Regularization of the inverse problem is a complex issue when using near-field acoustic holography (NAH) techniques to identify the vibrating sources. This paper shows that, for convex homogeneous plates with arbitrary boundary conditions, alternative regularization schemes can be developed based on the sparsity of the normal velocity of the plate in a(More)
We consider the inverse problem of reconstructing general solutions to the Helmholtz equation on some domain Ω from their values at scattered points x1, . . . , xn ⊂ Ω. This problem typically arises when sampling acoustic fields with n microphones for the purpose of reconstructing this field over a region of interest Ω contained in a larger domain D in(More)
This paper describes a method to obtain a perceptually relevant sparse representation of a sound signal. Based on matching pursuit (MP) and recent psychoacoustic data on time-frequency masking measured with Gabor atoms, a perceptual matching pursuit (PMP) algorithm is proposed. To obtain a good match between the masking model and the signal representation,(More)
Spirometry, blood gases, steady state diffusing lung capacity for carbon monoxyde, ductance for carbon monoxyde were determined in 27 obeses. In 13 of them we also measured closing volume. In 80 per cent of these patients we observed a decrease in expiratory reserve volume certainly due to a shift on the right of the chest wall volume-pressure curve. In 50%(More)
We measured lung volumes, closing volume (CV), alveolo-arterial oxygen difference (P(A-a)O2) and steady-state diffusing lung capacity per liter ventilation (DLCO/V) in 18 men immersed up to the neck in water. The subjects were divided into 3 groups, according to relative changes in P(A-a)O2 and DLCO/V. In group 1 (n = 6), P(A-a)O2 decreased and DLCO/V(More)
We have studied the maximal expiratory flow volume curves with air and with an 80% helium-oxygen mixture, using 12 normal and 33 asthmatic children chosen according to clinical, functional and immunological criteria. In the normal children, the average delta Vmax (difference between the maximal flow in HeO2 and in air at corresponding lung volumes) was 49%(More)
The recent theory of compressive sensing leverages upon the structure of signals to acquire them with much fewer measurements than was previously thought necessary, and certainly well below the traditional Nyquist-Shannon sampling rate. However, most implementations developed to take advantage of this framework revolve around controlling the measurements(More)
In this paper, we investigate the optimal ways to sample multichannel impulse responses, composed of a small number of exponentially damped sinusoids, under the constraint that the total number of samples is fixed &#x2014; for instance with limited storage / computational power. We compute Cram&#x00E9;r-Rao bounds for multichannel estimation of the(More)