Numerical Methods to Implement Time Reversal of Waves Propagating in Complex Random Media

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dc.contributor.advisorDr Michael Steer, Committee Memberen_US
dc.contributor.advisorDr Mansoor Haider, Committee Memberen_US
dc.contributor.advisorDr Jean-Pierre Fouque, Committee Co-Chairen_US
dc.contributor.advisorDr Gianluca Lazzi, Committee Chairen_US
dc.contributor.authorMehta, Kurang Jvalanten_US
dc.date.accessioned2010-04-02T17:59:45Z
dc.date.available2010-04-02T17:59:45Z
dc.date.issued2003-08-18en_US
dc.degree.disciplineElectrical Engineeringen_US
dc.degree.levelthesisen_US
dc.degree.nameMSen_US
dc.description.abstractA time reversal mirror is a device capable of receiving a signal in time, keeping it in memory, and sending it back into the same medium in the reversed direction of time. The main effect is the fascinating refocusing of the scattered signal, which is formed by sending the pulse into a complex medium, after time reversal through the same medium. The refocused signal is a pulse with shape similar to the initial pulse along with some low amplitude noise. This surprising effect has a great potential for application in domains such as medical imaging, underwater acoustics and wireless communication. Time reversal is studied in reflection and transmission. In both cases, we demonstrate the self-averaging properties of the time reversed refocused pulse. An accurate numerical method for simulating waves propagating in complex one-dimensional media is employed. Numerical simulations are used to reproduce the time-reversal self-averaging effect which takes place in randomly layered media. The effect of refocusing is enhanced in a regime where the inhomogenities are smaller than the pulse, which propagates over long distances compared to its width. Time Reversal can be implemented using several numerical methods including Transfer Matrix, Finite Difference Time Domain (FDTD) & Boundary Integral Methods. This thesis includes a comprehensive comparison of the methods in terms of speed and accuracy. The most efficient method for implementing time reversal is then used to obtain numerical evidence for potential use of a sliding window time-reversal technique for detecting a buried cavity/object inside the medium. The numerical methods are well adapted for generalization to the multi-dimensional case.en_US
dc.identifier.otheretd-05192003-160819en_US
dc.identifier.urihttp://www.lib.ncsu.edu/resolver/1840.16/960
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectFinite Difference Time Domain Methoden_US
dc.subjectBoundary Integral Methoden_US
dc.subjectTransfer Matrix Methoden_US
dc.subjectWave Propagationen_US
dc.subjectTime Reversalen_US
dc.titleNumerical Methods to Implement Time Reversal of Waves Propagating in Complex Random Mediaen_US

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