An Electromagnetic Interrogation Technique Utilizing Pressure-dependent Polarization

acoustic pressure;electric polarization;electromagnetic/acoustic interaction;electromagnetics

Raye, Julie Knowles ; Kazufumi Ito, Committee Member,H. T. Banks, Committee Chair,Hien T. Tran, Committee Member,Michael Shearer, Committee Member,Raye, Julie Knowles ; Kazufumi Ito ; Committee Member ; H. T. Banks ; Committee Chair ; Hien T. Tran ; Committee Member ; Michael Shearer ; Committee Member

University:North Carolina State University

关键词: acoustic pressure;    electric polarization;    electromagnetic/acoustic interaction;    electromagnetics;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/3560/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

This dissertation focuses on an interrogation technique that uses traveling acoustic wavefronts as a virtual reflector for an oncoming electromagnetic wave.Electromagnetic interrogation techniques in general have the potential for wide applicability in practical problems and this technique in particular enjoys that potential.We begin by developing a viablemodel for pressure-dependent orientational (Debye) polarization.We then incorporate it into a one-dimensional Maxwell system to describe the electromagnetic/acoustic interaction.This system may be generalized to include a wider class of electromagnetic behavior; we establish well-posedness, enhanced regularity, and convergence resultsfor this general system.Under the framework provided by the mathematical theory, we obtain computational results for sample forward and inverse problems relating to the interrogation technique.Our numerical algorithms for the forward problem involve finite difference approximations in time and finite element approximations with piecewise linear basis elements in space.Solving the inverse problem entails least squares minimization using a gradient-freeNelder Mead optimization routine.Finally, as a first step in developing a model in whichthe pressure wave may be modulated by the electromagnetic wave (unlike the one-way coupling in the model presented here), we consider the system describing an acoustic wave propagating through a layered medium.We derive a weak formulation for this system and present computational findings.