Supervision: Hervé Lissek

Project type: Semester project (master) Master thesis

Available

Nonlinear or time-varying systems have established a new paradigm in wave engineering as they push the limits of conventional materials. Nevertheless, the harmonic frequencies generated by the nonlinearity or the temporal modulation of the medium properties make it challenging to characterize their scattering properties. Matched sources minimize such constraints since the incident field is known (any reflection at the source is absorbed), thus reducing the number of unknowns to be resolved in the system.

Although extensively used in electromagnetic, matched sources are not widely developed in acoustics due to the highly reflective nature of electrodynamic speakers. To overcome this limitation, the matching condition can be achieved by active control. By sensing the pressure in front of a closed-box loudspeaker and applying a feedback control law that assigns a specific current, the effective impedance of the loudspeaker can be changed and designed, thus enabling impedance matching.

The project will consist of:

• a quick literature review on acoustic active control and matched sources

• the development of a numerical scheme (FDTD / Simulink) to realize an acoustic matched source

• the implementation of an experimental set-up to characterize the performance of the electrodynamic matched source at multiple harmonics

• the extension of the study to a broadband-matched source, by switching the electrodynamic source type to an actively controlled corona discharge actuator

Profile: Electrical engineering, Micro-engineering, Physics, Mechanics

Prerequisites: Acoustics, Electroacoustics

Learning outcome: linear active control for acoustics, acoustic measurement

Context: Theory/Physical Simulations (40%), measurement (60%)”