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SUMMARY:Analytic Mode-Matching at an Exceptional Point - Jane  Lawrie (Bru
 nel University)
DTSTART:20230207T133000Z
DTEND:20230207T141500Z
UID:TALK194761@talks.cam.ac.uk
DESCRIPTION:Exceptional points (which occur when two or more modes coalesc
 e) have long been associated with optimal attenuation in lined acoustic wa
 veguides.&nbsp\; In recent years\, with a view to optimising sound absorpt
 ion\, some effort has gone into designing liners that generate exceptional
  points (EPs) at specified frequencies. However\, analytic modelling of ac
 oustic scattering in the presence of an EP is not well developed\, with mo
 st authors relying on standard methods applied close to (but not at) EP co
 nditions. Indeed\, exact treatment requires care since the mathematical sy
 stem under-pinning the scattering process is degenerate. This talk present
 s an analytic mode-matching approach to modelling the scattering of a plan
 e wave travelling towards the junction of a rigid duct with a lined duct a
 t EP conditions. Both EP2 and EP3 (coalescence of two and three modes resp
 ectively) are considered. The enhanced mode-matching scheme is shown to be
  valid and numerically robust\, and it is anticipated that it will be stra
 ightforward to adapt to a wide range of applications involving complex sym
 metric operators. [In collaboration with E Perrey-Debain and B Nennig.]
LOCATION:Seminar Room 1\, Newton Institute
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