Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"Dispersive Media"”.
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Particle filtering for frequency estimation from acoustic time-series in dispersive media
Acoustic signals propagating in the ocean carry information about geometry and environmental parameters within the propagation medium. Accurately retrieving this information leads us to effectively estimate parameters that are of utmost importance in environmental studies, climate monitoring, and …
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Adapting Seismic Processing Techniques for Data Preconditioning in Radar Imaging of Highly Dissipative and Dispersive Media
… in the presence of highly dissipative and dispersive breast tissues. Microwave imaging and seismic imaging deal with analogous problems. In seismic imaging, tremendous efforts have been invested in developing data analysis and preconditioning techniques to render the accurate graphical …
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Phase-space analysis of wave propagation in homogeneous dispersive media and its relationship to catastrophe theory
… approach to wave propagation in homogeneous dispersive media is discussed which has several advantages by comparison to conventional techniques, such as the stationary phase method, ordinary ray tracing, etc. This approach, which is based on the wave-kinetic theory, <sup>7/8</sup> is used to …
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Investigation of explicit finite-element time-domain methods and modeling of dispersive media and 3D high-speed circuits
… Second, the modeling of doubly lossy and dispersive media is incorporated into the DFDD method, which demonstrates the accuracy and efficiency in the comparative study, but can only model non-dispersive media in its original version. The phase error analysis indicates that the enhanced …
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The rise and fall of structure in physics : polaritonic photonic crystals, melting, and min-protein oscillations
… study photonic crystals composed of polaritonic media, focusing on the unique features of the band structures and Bloch states in dispersive media with and without losses. I discuss three novel localization phenomena in these structures: node switching, flux expulsion, and negative effective …
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Advanced Time-Domain Finite-Element Method for Electromagnetic Analysis
… TDFEM schemes, the TDFEM modeling of general dispersive media, and the general stability analysis of the TDFEM. First, fast two-dimensional and three-dimensional time-domain finite element-boundary integral methods are developed for analyzing open-region electromagnetic transient scattering. …
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A Single-Field Finite-Difference Time-Domain Formulations for Electromagnetic Simulations
… cases for linear, isotropic, homogeneous and non-dispersive as well as dispersive media.</p> <p>To compare the single-field updating equations with the traditional ones, two-dimensional transverse magnetic, two-dimensional transverse electric and one-dimensional electromagnetic problems are …
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Numerical Reconstruction and Applications of Acoustic and Electromagnetic Ultra-Wideband Localized Pulses Generated by Dynamic Aperture Antennas
… properties of LWs propagating through dispersive media modeled by the Klein-Gordon equation. It is demonstrated that contrary to expectation, the depletion of the spectral components of the LW Klein-Gordon field may be slower than that associated with the free space scalar field. …
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Optical Precursor Behavior
… the propagation of optical pulses through dispersive media forms the basis for optical communication, medical imaging, and other modern technological advances. Integral to this control and understanding is the ability to describe the transients which occur immediately after the onset of a …
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Dispersion, controlled dispersion, and three applications
Causality dictates that all physical media must be dispersive. (We will call a medium dispersive if its refractive index varies with frequency.) Ordinarily, strong dispersion is accompanied either by strong absorption or strong gain. However, over the past 15 years several groups have demonstrated …
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The state of the art time-domain wavefield imaging using a discontinuous Galerkin forward-backward time-stepping method
… DGM-FBTS and present it, for the first time, for dispersive media. The electromagnetic (EM) two-dimensional non-dispersive Transverse Magnetic (TM) DGM-FBTS is compared to Frequency Domain (FD) imaging algorithms for synthetic and experimental imaging targets in terms of computational cost, the …
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Modeling and design of near-field antennas with periodic structures
… from periodic structures. The modelling of dispersive media is incorporated into a three-dimensional DGTD scheme, which is capable of studying plasmonic periodic structures at optical frequencies. Various numerical examples are presented to demonstrate the applications of the proposed …
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Microwave Tomography Using Stochastic Optimization And High Performance Computing
… capable of modelling complex, heterogeneous, and dispersive media using the Debye model. A detailed explanation of the dispersive FDTD is presented herein. The system uses scattered field data due to multiple excitation angles, frequencies, and observation angles in order to improve target …
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Sensor arrays for the measurement of dispersive, flexural waves in structures for signal-to-noise ratio enhancement and angle of arrival determination
… techniques are considered with applications to dispersive flexural waves where the propagation velocity is not constant but dependent on frequency. The theory is validated through experiments with harmonic and broad band applications. The test apparatus consisted of a long thin beam with …
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Modeling the interaction of light with photonic structures by direct numerical solution of Maxwell's equations
… and the time domain description of temporally dispersive media. It addresses also the plane wave representation of an electromagnetic field distribution, mainly the far field one. The Kirchhoff formula is described and deduced, to calculate the angular radiation distribution around a scatterer. …
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Analysis of periodic structures using finite-difference time-domain method
… a new algorithm is developed to analyze dispersive periodic structures, the algorithm is easy to implement and efficient in both computational time and memory usage. All the developed algorithms are validated through several numerical test cases.