Research, teaching in Acoustics
Engineer in electronics
presently posdoctoral fellow
Laboratoire d'Acoustique de l'Université du Maine (LAUM, France),
Signal processing group
| 28 years old
born : Cholet, France, 10-04-1972 Citizenship : French Single |
Address : Laboratoire d'Acoustique de
l'Université du Maine
UMR - CNRS 6613 av. O. Messiaen, 72 085 Le Mans cedex 9 Tél. : 02.43.83.32.79 (office) 02.43.83.35.20 (fax) E-mail : christophe.ayrault@univ-lemans.fr |
| Education |
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Education
| 1996 - 1999 | PhD in acoustics, LAUM, Material group. |
| 1995 - 1996 | Degree for PhD studies in applied acoustics, University of Le Mans, France |
| 1992 - 1995 | Engineer diploma in electronics,
Ecole Nationale Supérieure d'Electronique, d'Informatique et de Radiocommunications de Bordeaux (ENSEIRB), France Two years of non-specialized training and one year of specialization in "Image and Communication Technologies" |
Experience
| 2000 – 2001 | Cities acoustics, room acoustics,
signal processing :
Post doctoral fellow (LAUM, Signal processing group) for a National project on sound propagation in streets Optimization of a street scale model for the study of sound propagation in urban areas Validation of propagation models based on scattering theories |
| 1999 - 2000 | Ultrasonic characterization of
materials, signal processing :
Research and teaching assistant (LAUM, Materials et Signal processing groups). Time -frequency analysis of ultrasonic signals for porous materials characterization Characteristic parameters estimation of materials from interfaces reflexions. |
| 1996 - 1999 | Ultrasonic characterization of
materials :
PhD (LAUM, Materials group). Influence of static pressure on ultrasonic characterization of porous media. Study of the weak scattering regime. Keywords : porous media, ultrasounds, scattering, experiments, numerical inversion Realizations : - development of a variable static pressure set up for ultrasonic measurements of velocity and attenuation in porous materials : caracterization of highly damping materials - Experimental study of the weak scattering regime Abstract |
| 1996,
4 months |
Signal processing :
Research project (LAUM, Signal processing group), contract realized for the research department of EDF (Electricité de France). Spectral analysis of random sampled signals in Laser Doppler Anemometry Comparison of numerical techniques |
| 1995,
3 months |
Multimedia:
Engineering project – Maison des Sciences de l'Homme d'Aquitaine, Bordeaux. Development of a multimedia application client (on Windows and Macintosh) - server (on Unix) |
| 1994,
4 months |
Power electronics :
Engineering project – Laboratoire d'Audiologie Expérimentale, INSERM, Bordeaux. Realization of an electromagnetic prototype for auditory nerves diagnosis |
Publications
Communications
National congresses :
4- Ayrault C., Moussatov A., Castagnede
B. : "Influence de la pression statique sur la caractérisation de
matériaux poreux", 14ème Congrès Français de
Mécanique, Toulouse, august 29 - sept. 3 1999.
5- Ayrault C., Moussatov A., Castagnede
B. : "Caractérisation ultrasonore de matériaux poreux en
régime faiblement diffusif par variation de pression statique",
6èmes Journées d'Acoustique Physique Sous-Marine et Ultrasonore,
Blois, may 5 - 6 1999
Submitted communication :
6- Ayrault C., Simon L. : "improvement
of sources and reverberation time estimation for the study of sound propagation
in a street scale model", submitted to the 17th International Congress
on Acoustics, Rome, sept. 2001.
Other skills
| Programming : | C, Fortran, Matlab, Assembleur 68 000, |
| Systems : | Unix, IBM DOS, Windows, Macintosh, |
| Software : | LabView (interface and processing), MLSSA, Catt Acoustic
(rooms acoustics),
Acoubat (building acoustics) |
| Formation : | informatic nets, systems, multimedia (ENSERB) |
Other informations
- Member of the LAUM council (1999 - 2001),- amateur saxophone player, member of the big band of the university of Le Mans and a saxophones quartet,
- Responsible of the music club of ENSEIRB (1993 - 1995),
- Co-organizer (1998) and organizer (1999 - 2000) of the european festival of university big bands of
Le Mans, l'Oeuf de Jazz
PhD Abstract : Ultrasonic methods
are a simple and efficient mean for characterization of the acoustic behaviour
of porous media. Under the assumption of rigid skeleton, measurement of
speed and attenuation yield three characteristic parameters : tortuosity
and two characteristic viscous and thermal lengths. Recently validated,
these methods are sometimes limited by excessive damping properties or
scattering phenomenon. The contribution of this thesis is the development
of a new method palliating these inadequacies.
Previous measurements are performed at fixed frequency
and for different values of static pressure of the saturating fluid (from
0 to 7 bars). Validation is achieved by measurements of known polyurethane
foams. Important dynamic gain, obtained by density increase of propagative
medium, solves problems of high damping. Study of the frequency influence,
in the [30-600] kHz range, shows scattering, weak in foams and greater
in glass beads samples. Assumption of separation of losses due to viscothermicity
and scattering, proposed by Nagy et al. (96), is applied with success at
the time of parameters extraction in scattering regime. However, weak scattering
models (Rayleigh regime) describe well only the case of high porosity (foams).
Using Biot theory for vibrating skeleton, simulations
show that structural waves appear only for a few materials in the considered
pressure range. This information confirms the applicability of the method
to a wide range of highly resistive materials. The last study concerns
the existence of membranes inside resistive polyurethane foams, which makes
that the method fails. Pressure increase allows to get parameters by numerical
inversion from temporal signals with great signal to noise ratio. Results
indicate a particular behaviour : apparent tortuosity varies with pressure.