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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 101 for “"Pinhole"”.
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Fixed and Adaptive Multiple-Pinhole Apertures for Brain SPECT Imaging
… the design and implementation of novel multiple-pinhole aperture systems with both fixed arrangements of "always open" pinholes as well as adaptive ones where pinhole diameters and "open" pattern are adjustable. The fixed multi-pinhole aperture was developed to mount to an existing clinical …
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The conceptualization and parameterization of a gaseous detector rasterizing pinhole gamma camera
… of a gaseous detector rasterizing pinhole gamma camera. In this thesis, there is a literature review that describes the historical development of gamma imaging, a technical background that aims to give the reader the prerequisite background knowledge, a methodology, and, a result …
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Applications of Multi-Pinhole Gamma Camera Collimation to Tomography and Image Enhancement
Recently, multi-pinhole gamma camera collimation has been introduced in the field of emission tomography. This collimation process simultaneously produces several images covering a limited angular range, which may then be recombined to obtain tomographic slices of the object imaged. This study has …
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On-board Robotic Multi-pinhole SPECT System for Region-of-interest (ROI) Imaging
… too long for on-board imaging. A robotic multi-pinhole SPECT system was proposed in this dissertation to provide shorter imaging time by using a robotic arm to maneuver the multi-pinhole SPECT system around the patient in position for radiation therapy. </p><p>A 49-pinhole collimated SPECT …
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Incidence and Costs of Pinhole Leak Corrosion and Corporate Cost of Capital Borrowing
… factors influencing the occurrence and costs of pinhole leak corrosion as well as the household decisions for corrosion prevention and plumbing material selection. Three mail surveys of households were used to elicit the experiences with leaks as well as the optimal corrosion prevention and …
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An Assessment and Modeling of Copper Plumbing pipe Failures due to Pinhole Leaks
Pinhole leaks in copper plumbing pipes are a big concern for the homeowners. The problem is spread across the nation and remains a threat to plumbing systems of all ages. Due to the absence of a single acceptable mechanistic theory no preventive measure is available to date. Most of the present …
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The Design and Characterization of a Multiple Pinhole Collimator and Its Applications in Biopharmaceutics
A 4-pinhole collimator was designed to image small objects and its characteristics were studied. The field of view formed by this collimator was a conically-tipped pyramid with a minimum object distance of 3 cm. The line-spread function at 8 cm from the collimator had a full-width-half-maximum of …
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Proposta de metodologia para dimensionamento da espessura de núcleos argilosos em barragens baseada em ensaios Pinhole
… de enrocamento, baseada na realização de ensaios pinhole. É proposto estudar até quanto é possível reduzir o volume de solo argiloso compactado, por meio da utilização de núcleos mais esbeltos, adotando-se um critério de gradiente hidráulico de carreamento deste material. Neste estudo está também …
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Analysis of Sans Transmission Data from Highly Absorbing Samples with Thickness Non-Uniformity and Pinhole Defects
Made available in DSpace on 2017-07-06T18:42:23Z (GMT). No. of bitstreams: 3 Barber_Nathan_R_MS.pdf: 32484155 bytes, checksum: c0e4681232f1c1f64f9d779adf81a73e (MD5) Barber_Nathan_R_MS_ABS.pdf: 611841 bytes, checksum: 2a58b6037413e2eb8a47b78e4ea8431b (MD5) license.txt: 4813 bytes, checksum: …
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Miniaturized 3--D Mapping System Using a Fiber Optic Coupler as a Young's Double Pinhole Interferometer
… coupler were brought close together to form the pinholes of a Young's Double Pinhole Interferometer. This provides the advantages of this simple interferometer without the disadvantage of power loss by the customary method of spatially filtering a collimated laser beam with a pair of pinholes. …
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Implementation of scattering pinhole diagnostic for detection of fusion products on CR-39 at high particle fluence
… particle tracks would overlap. A scattering pinhole has been implemented in order to reduce the fluence on the CR-39. This paper details the design and implementation of a scattering pinhole to detect protons born from D3He nuclear reactions: D +3 He = p+(14.7MeV) + [alpha](3.7MeV). To do so, …
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A Discrete Choice Mean Variance (EV) Cost Model to Measure Impact of Household Risk from Drinking Water Pipe Corrosion
… their home plumbing systems in the event of a pinhole leak, a tiny pin-sized hole that forms in copper, drinking-water pipes. These leaks can cause substantial damage and cost homeowners thousands of dollars in repairs. Since pinhole leaks are not related to the age of pipe material, a …
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Structure and epitaxy studies of cobalt silicide/silicon heterostructures
Interfacial pinhole formation was identified at the CoSi/Si interface and involves several active mechanisms which include locally enhanced silicon and cobalt diffusion, silicide spike formation during CoSi thin film growth, and volumetric contractions during the CoSi $\to$ CoSi$\sb2$ phase …
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A Comprehensive Methodology For Well Ramp-up of Open Hole Stand-Alone Screen Completions
… non-uniform filter cake clean-up or presence of “pinholes” resulting in concentrated inflow around the wellbore. A combination of laboratory return permeability tests, CT scans and a developed reduced order model determines the pinhole size and filter cake properties to calculate the total pinhole …
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IMPROVING RESOLUTION IN WRIST SPECT WITH CONVERGING COLLIMATORS AND CT ANATOMICAL PRIORS
… wrist SPECT resolution can be improved by using pinhole collimators and by incorporating anatomical prior information. Phantom experiments have shown that a 3mm single-pinhole system can achieve a 4mm resolution at clinical count levels, but a 3mm resolution required 4-times as many counts. …
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A surgical confocal microlaparoscope for real-time optical biopsies
… tissue. In contrast, the results show that multi-pinhole apertures such as a Nipkow disk or a linear pinhole array can achieve nearly the same depth performance as a single pinhole aperture. The model was used to determine the optimal aperture spacing for the multi-pinhole apertures. The confocal …
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High-resolution Optical Scanning Holography
… first approach is to use only the experimental pinhole hologram recorded to correlate with the hologram of the object to give the reconstruction of the section. The second approach is to use the propagated pinhole hologram to reconstruct at an arbitrary depth. Finally, the third approach is to …
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Architecture of uncertainty
… given time and place. In this investigation the Pinhole camera was used as a device for capturing photographic images of an urban place. The images produced by the pinhole cameras are representations of the existing place and its experience. The representation of a place generated by the device …
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