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 121 for “"Fresnel"”.
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Fresnel phase plates as reconfigurable microfluidic lenses
In this study, Fresnel phase plates were tested as reconfigurable lenses. The lenses were constructed from a Fresnel pattern which was transferred to a silicon substrate via photolithography. A layer of PDMS was spin-coated on the substrate and cured to produce the lens. This lens was attached to a …
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An analytical study of the Fresnel wave-surface
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Physics, 1903.
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Image grating metrology using a Fresnel zone plate
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
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Photoinduced Fresnel reflectors in germanium-doped optical fibers
… laser. These refractive index changes cause Fresnel reflections at the boundary of the higher photoinduced index change and the lower index in the unexposed core. The boundary of the two refractive indices may be considered a low reflectance mirror. Several techniques have been explored to …
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Multipath "Fresnel Zone" Routing for Wireless Ad Hoc Networks
… In this work, we propose the multipath “Fresnel zone” routing (FZR) algorithm for wireless ad hoc networks. FZR constructs multiple parallel paths from source to destination based on the concept of “Fresnel zones” in a wireless network. The zone construction method assigns intermediate …
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Measurements of Fresnel-drag using a passive ring resonator technique
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1983.
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EXPERIMENTALLY MEASURING THERMAL CONDUCTIVITY IN WARM DENSE MATTER USING FRESNEL DIFFRACTIVE RADIOGRAPHY
… This dissertation details the development of the Fresnel Diffractive Radiography platform, which uses X-ray interference effects - refraction and diffraction - to determine the sub-micron evolutions in density gradients at warm dense matter interfaces. These evolutions are a response to heat …
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Diseño óptimo de reflectores lineales Fresnel de pequeña escala para uso urbano
… presenta un estudio de los reflectores solares Fresnel a pequeña escala y sus usos para la obtención de energía eléctrica y/o térmica mediante su instalación en terrazas o azoteas de edificios urbanos. En este problema de Ingeniería intervienen un gran número de variables a optimizar, lo cual lo …
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Fresnel-focusing and bessel-beam integrated optical phased arrays for optical trapping applications
… patterns in the far field. In this thesis, Fresnel-lens-inspired focusing integrated optical phased arrays are demonstrated for the first time and proposed as a method for chip-based optical trapping. These systems focus radiated light to tightly-confined spots in the near field above the …
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Theory and design of integrated optical isolators and broadband couplers using Fresnel zone plates
… vertical coupler. The structure utilizes a Fresnel lens, or more advanced integrated optics, placed above a short, ridge and deep etched, vertical coupler in a Si waveguide. This optics is placed in order to match the radiating fields to the fiber mode. We use semivectorial simulations with …
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Análisis de la influencia de la inclinación longitudinal en el rendimiento de reflectores lineales Fresnel de pequeña escala en aplicaciones urbanas
En esta Tesis Doctoral se presenta el análisis de la influencia de la inclinación longitudinal en el rendimiento de reflectores lineales Fresnal de pequeña escala en aplicaciones urbanas, utilizados en sistemas fotovoltaicos de baja concentración y en sistemas termo solares. Esta tecnología …
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Contribución a la teoría de diseño y a la tecnología de las lentes de FresNel para su uso como concentradores en aplicaciones fotovoltaicas
… aspectos relacionados con el empleo de lentes de Fresnel como concentradores fotovoltaicos: Por un lado se analiza un concentrador de una o de dos etapas en el que la primera etapa está constituida por una lente de Fresnel de forma arbitraria (plana, curva, etc.) en el supuesto de que la segunda …
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High-energy approximations to nuclear scattering
… We distinguish the eikonal expansion and the Fresnel expansion and interpret their physical meaning in optical terms. A "Fresnel approximation" is defined as a partial sum of the eikonal expansion which describes Fresnel diffraction effects. In Fresnel approximation we derive, by means of a …
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Resolving Small Objects Using Seismic Traveltime Tomography
It is often claimed that the first Fresnel zone associated with the dominant frequency represents the spatial resolution limit of traveltime tomography. We show, however, that the relevant Fresnel limit for tomographic resolution is the maximum, not the dominant frequency in the data. For …
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Using GPS bistatic signal for land and ocean remote sensing in South Africa
… and concentrates on reflection points and Fresnel zones. The CPS receivers are placed at different coastal regions within South Africa, and the simulation of the reflection points and Fresnel zones are observed as the CPS satellites pass over South Africa. The East London area was chosen as …
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Analysis of radiation mechanism and polarizing properties of metamaterials
… through a pair of crossed-polarizers, and 2. Fresnel coefficients of a single polarizer. The expressions for the transmittance and the Fresnel coefficients are obtained analytically using the kDB method. A novel procedure to determine the angles of transmission of the ordinary and …
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Solar thermal collector system modeling and testing for novel solar cooker
… This thesis looked at prior research on glazing, Fresnel lenses, and absorber surface treatments to identify and evaluate elements for use in the collection system. Borosilicate glass, with a thermal conductivity of 1.005 W/mK and a solar transmittance of 0.91, and flat black paint, with …
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Twin-image problems in optical scanning holography
… beam can be a time-dependent Gaussian apodized Fresnel zone pattern. We derive the resolution achievable with such a scanning beam. We then discuss the use of a larger and a smaller Fresnel zone pattern for holographic recording to investigate twin-image noise which results in the unwanted image …
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Numerical simulation of optical wave propagation through random media
… angular-spectral representation of the Huygens-Fresnel diffraction formula are used. For the wave-kinetic numerical method, several different levels of approximations are introduced, and the region of validity of those approximations is studied by single-realization calculations. Simulation …
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