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Retrofocusing of Acoustic Wave Fields by Iterated Time Reversal

In English

Författare

Summary, in English

In the present paper an iterative time-reversal algorithm that retrofocuses an acoustic wave field to its controllable part is established. For a fixed temporal support, i.e., transducer excitation time, the algorithm generates an optimal retrofocusing in the least-squares sense. Thus the iterative time-reversal algorithm reduces the temporal support of the excitation from the requirement of negligible remaining energy to the requirement of controllability. The time-reversal retrofocusing is analyzed from a boundary-control perspective where time reversal is used to steer the acoustic wave field towards a desired state. The wave field is controlled by transducers located at subsets of the boundary, i.e., the controllable part of the boundary. The time-reversal cavity and time-reversal mirror cases are analyzed. In the cavity case, the transducers generate a locally plane wave in the fundamental mode through a set of ducts. Numerical examples are given to illustrate the convergence of the iterative time-reversal algorithm. In the mirror case, a homogeneous half space is considered. For this case the analytic expression for the retrofocused wave field is given for finite temporal support. It is shown that the mirror case does not have the same degree of steering as the cavity case. It is also shown that the pressure can be perfectly retrofocused for infinite temporal support. Two examples are given that indicate that the influence of the evanescent part of the wave field is small.

Publiceringsår

2004

Språk

Engelska

Sidor

1954-1986

Publikation/Tidskrift/Serie

SIAM Journal on Applied Mathematics

Volym

64

Issue

6

Dokumenttyp

Artikel i tidskrift

Förlag

Society for Industrial and Applied Mathematics

Ämne

  • Other Electrical Engineering, Electronic Engineering, Information Engineering
  • Electrical Engineering, Electronic Engineering, Information Engineering

Status

Published

Forskningsgrupp

  • Electromagnetic theory

ISBN/ISSN/Övrigt

  • ISSN: 0036-1399