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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 160 for “"Apertures"”.
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The diffraction of monsters from complex apertures
The research presented in this MSc thesis is concerned with understanding the way incoming electromagnetic waves are diffracted by various different types of scattering screens. These classes of problem are fundamental in the laser optics community, and within the arena of wave physics more …
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Fixed and Adaptive Multiple-Pinhole Apertures for Brain SPECT Imaging
Single-Photon Emission Computed Tomography (SPECT) is a medical imaging modality where a radiopharmaceutical's emissions are captured with one or more gamma cameras deployed about the patient. During tomographic acquisitions, the SPECT camera(s) collect gamma-ray projection images created by …
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Fiber optic hydrogen sensing utilizing facet etched palladium nano-apertures
… optic hydrogen sensor based on facet etched nano-apertures in palladium films. Palladium is known to absorb hydrogen, resulting in a change in the optical and structural properties of the film which can be probed by measuring the transmission through the aperture. These sensors showed sensitivity …
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Modeling electrically small apertures using the finite difference-time domain method
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
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Near field coupling between elements of a finite planar array of circular apertures
The mutual admittance between two waveguide-fed apertures radiating into a multilayered region is expressed as a double integral of a combination of the Fourier transforms of the respective aperture electric fields and the solutions to a set of transformed wave equations for the layered region. The …
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Optical fibre surface plasmon resonance sensors based on a metallic array of sub-wavelength apertures
… based on a metallic array of sub-wavelength apertures are investigated. Metallic sub-wavelength apertures may be designed to support surface plasmon resonances that are sensitive to the surrounding environment when embedded at the end-face of an optical fibre. Factors contributing to the …
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Optical transmission and emission behavior of subwavelength apertures flanked by periodic structures in gold films
Includes bibliographical references (pages 104-111).
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Strain-controlled disorder-defined apertures for optical mode control in vertical-cavity surface-emitting lasers
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-12-01
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Strain-controlled impurity-induced disordering for apertures in single-mode vertical-cavity surface-emitting lasers
… work, the fine control of Zn diffusion fronts in apertures formed using impurity-induced disordering is presented. By tailoring the diffusion mask strain, the diffusion front curvature of the impurity-induced disordering aperture can be controlled. Through modifying the composition of SiN$_{x}$ …
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Fascial Spaces and Communicating Apertures Found in the Neck. A Visual Learning Module of The Retropharyngeal Space
The complex existence of fascial spaces in the head and neck remain vague and difficult to visualize for prospective students. This may be due to historical disagreement on the nomenclature and having only cross-sectional images, which prove inefficient in illustrating every aspect of a fascial …
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Enhanced beam quality and polarization stability in oxide-confined Vertical-Cavity Surface-Emitting Lasers via anti-phase optical coatings and disorder-defined apertures
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01
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Analysis of three-dimensional field distributions for focussed unapodized/apodized annular beams
… of focal shift in focused beams using unapodized apertures has been well documented. However, not much work has been done on apodized apertures. In this thesis we use a Fourier-Optic approach to analyze the field distribution of a focused beam around the region of geometrical focus. The analytical …
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The Effects of Diffuser Exit Velocity and Distance Between Supply and Return Apertures on the Efficiency of an Air Distribution System in an Office Space
<p>The distance between supply air diffusers and return air grilles is an important design parameter that has not been properly investigated. Sometimes, design and installation constraints force the engineer or the contractor to place the return duct close to the supply duct which can have a huge …
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Synthetic aperture sonar for sub bottom imaging
… problems associated with implementing synthetic apertures in sonar may be overcome by applying the technique to sub-bottom imaging. The use of a low frequency aids both penetration of the sediment and the attainment of long coherent apertures. The implementation of synthetic apertures realises a …
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Method of Moments Analysis of an Aperture in a Thick Ground Plane
… the ground plane are of arbitrary shape. The apertures at both ends of the cavity are also of arbitrary shape. The structure is illuminated by an incident plane electromagnetic wave. The Green's function for this complicated problem is almost impossible to determine. Therefore the surface …
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Optical sub-diffraction limited focusing for confined heating and lithography
… of the processing laser.</p> <p>Nanoscale ridge apertures are devices with a great potential to confine light energy. Such apertures have been experimentally proven to create very small lithography features. We believe that these apertures can be further modified in order to achieve a practical …
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Particle swarms in confining geometries
… (two finite parallel plates), a range of apertures exists in which swarms travel more quickly than swarms in larger apertures. This behavior was observed in 3 separate experimental sets using different combinations of bulk fluid and particles. In fractures with variable apertures, swarms …
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Programmable Aperture Photography: An investigation into applications and methods
… applications. Research has shown that coded apertures are far superior to traditional circular apertures for various tasks. A variety of coded aperture patterns have been proposed and developed over the years for use in various applications such as defocus deblurring, depth estimation and …
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Aperture: An architecture to amplify aspects of competitive swimming
… with four specifically designed architectural apertures that present the extraordinary motion of the swimmer, especially to the younger general public. The focus will be on the motion of swimming below and above the surface of the water. Below the water surface, the approaching swimmer and the …
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Capacity of and coding for multiple-aperture, wireless, optical communications
… systems that use multiple transmit and receive apertures. These apertures provide redundant replicas of the transmitted message to the receiver, each corrupted separately by the atmosphere. Reliable communication occurs when not all of these paths are deeply faded. We quantify the maximum rate …
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