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 20 of 51 for “"periodic structure"”.
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Single Layered Periodic Structure Loaded Textile Patch Antennas
… provides an investigation of a Single Layered Periodic Structure Loaded Textile Patch Antenna with probe feed excitation. Specifically, this thesis is concentrated on the application of wearable antenna arrays with space suit, since this thesis has collaboration with the University of North …
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Response of periodic structures
Periodic structures are defined as structures consisting of identical substructures connected to each other in identical manner. In chapter I, the response of periodic structures to harmonic excitation is described by a matrix difference equation. The solution of the matrix difference equation can …
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Control of Sound Radiation From Structures with Periodic Smart Skins
… of the radiated sound power from a vibrating structure is proposed. The skin has a periodic structure and continuously covers a vibrating beam. Thus, this skin decouples the vibrating structure from the acoustic field by modifying the wavenumber spectrum of the radiating surface. First, …
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Propagation of electromagnetic waves in spatially dispersive inhomogeneous media
… with a common interface, and those with a periodic structure. For a material made of two homogeneous regions joined together we establish a set of boundary conditions to describe the behaviour of waves at this interface. These boundary conditions are additional to the standard ones provided …
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Scattering matrix analysis of photonic crystals
… photonic crystal which consists of a periodic array of parallel rods with circular cross sections. Without making any assumptions about normal incidence, single mode propagation, and sufficient inter-scatter separation in the direction of propagation, we show how to compute the …
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Applications Of Linear And Nonlinear Optical Effects In Liquid Crystals
… for the past decades. Aside from the variety of structures they can form, they exhibit a vast range of optical phenomena. Many of these phenomena found applications in technology and became an essential part of it. In this dissertation thesis we continue the line to propose a number of new …
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Efficient Spectral-Element Methods For Acoustic Scattering And Related Problems
… scattering problems, and nonlinear fluid-structure interaction problems.</p> <p>For the scattering problems, two cases are considered: 1) the scattering from a doubly layered periodic structure; and 2) the scattering from doubly layered, unbounded rough surface. For both cases, we first …
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Synthesis and characterization of high thermal conductive polymers and fabrication of polymer based thermal strap
… due to its organic nature and amorphous structures. In the late 20th century, electrically conductive polymers has been discovered. Thermally conductive polymers, however, were not demonstrated until the recent decades. Polymers are shown to have great potential in thermal conduction, …
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THEORY, FABRICATION, AND EXPERIMENTATION OF PHONONIC CRYSTALS IN MEMS AT MICRO/NANO SCALE: ENGINEERING OF THERMAL AND RF PHONONS TO APPLICATIONS IN THERMOELECTRICS AND MICRORESONATORS
… (PnCs) are novel materials comprised of a periodic structure of inclusions in a matrix. This periodic arrangement creates phononic bandgaps, and modifies phononic bandstructures of a material. Such a property offers promising applications at the micro and nano scales to engineer acoustic …
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The influence of anisotropy of the microstructure on the overall elastic-plastic response of fibrous metal matrix composites
… class of metal-matrix composites with a periodic structure, the influence of anisotropy of individual constituents on the overall response of the material has been investigated. Two classes of fibers are considered: boron (isotropic) and graphite (transversely isotropic). The plastic …
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Frequency selective surfaces with lumped and time-varying loads, variable surface impedance, and multiple screens
… for the spectral domain analysis of thin, planar periodic structures can be applied to a limited class of surface geometries. Since the frequency response of a periodic structure is dependent upon the geometry of the surface, a typical approach to changing the response is to modify the geometry. …
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Measurement of the chemical potential of thin helium films
… H$\sb2$ substrates in the T = OK limit reveal a periodic structure not corresponding to whole layers. We analyze the data in two extreme limits. First, treating the helium film as an incompressible, continuous fluid, the data indicate that the chemical potential has a contribution proportional to …
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Analysis of periodic structures using finite-difference time-domain method
Periodic structures are of great importance in electromagnetics these days due to their wide range of applications such as frequency selective surfaces (FSS), electromagnetic band gap, periodic absorbers, metamaterials and many others. The aim of this work is to develop several algorithms to …
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Imaging of absolute electrical properties using electroquasistatic and magnetoquasistatic sensor arrays
… located on a single plane and have a spatially-periodic structure. The sensor operates as a two-port device with one conductor used to excite the sensor and a second conductor used to sense the response to test materials. Existing measurement capabilities are extended: 1. Multiple sensing …
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Coherent micromanipulation of 1-D BEC in designed potentials
… the atomchip has to offer the miniaturization of structures and the integration of different devices (resonators, light fields, permanent magnets) are key factors. We have devised a method to micro-engineer the trapping potentials by sculpturing the chip, overcoming some limitations of the …
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Configurable multi-port radiators
… project introduces the concept of a multi-port periodic antenna for generic beam synthesis in 2D apertures. We propose the use of a periodic structure based on a strategically designed unit cell excited at its boundaries, forming a multi-port traveling wave structure. We introduce an analytical …
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Style in Bossuet's 1662 Lenten Sermons: A Method of Rhetorical Analysis
… dialogismus, figures of indirection, and periodic structure, far from being a mere exercise in ""empty form,"" suggests a consciously constructed argumentative strategy aimed at mediating a social and political context that could not have been more volatile."
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Probabilistic vibration analysis of nearly periodic structures
The localization of modes of nearly periodic structures causes a concentration of energy in one part of the mode shape. It occurs for a disordered structure with weakly coupled subsystems. The forced excitation of localized modes may affect the maximum response amplitude of the system. Two nearly …
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Waves in Anisotropic and Birefringent Artificial Dielectrics
… particular dielectric studied is comprised of periodically spaced square arrays of thin square metallic obstacles. The major objectives of this study are first, to determine why the lenses previously built with this material failed to perform properly, and second, to design a functional lens if …
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Towards broadly-tunable CMOS-compatible silicon light sources in the near-infrared
… the near-infrared (800 to 1600 nm) from a simple periodic silicon grating. The light emission is generated by spontaneous emission from these gratings interacting with low-energy free electrons (as low as 2 keV) and is recorded in the silicon transparency window. We develop time-domain numerics …
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