Jacques Lewalle

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Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role. The NASA STI Program Office is operated by Langley Research Center, the Lead Center for NASA's scientific and technical information.(More)
Multiunit electrophysiological activity recorded by gross electrodes from the olfactory nerve was analyzed by wavelet decomposition, a relatively new method of signal processing. The analysis was run on data from the unstimulated olfactory system as well as on data evoked in response to six different odorant stimuli. Like Fourier analysis, wavelet analysis(More)
This study was prompted by results obtained in a series of experiments on turbulent boundary layer manipulation [1, 2] by the wake of a cylinder. Pseudo-streamlines reproduced on Fig. 1(a) strongly suggest the presence of an asymmetric vortex street that overrides the boundary layer turbulent structures normally observed. This raises the question of the(More)
Fluid turbulence is undoubtedly a complex phenomenon, but the relation between the fundamental laws and the emergence of large-scale coherent eddies from differential interactions in a random background has remained elusive. Such a connection is attempted in this paper. The key analytical step is to express the Navier-Stokes equations in the Hermitian(More)
The ‘triad interactions’, arising from the spectral resolution of the nonlinear terms in the Navier-Stokes equations, have so far not been substantially modified in the wavelet representation. In this paper, the multiscale interactions are captured by exact expressions evaluated at a single scale of the Mexican hat wavelet coefficients: the larger-scale(More)
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