Thesis (Ph.D.) - University of Glasgow, 2008. / Ph.D. thesis submitted to the Faculty of Information and Mathematical Sciences, Department of Statistics, University of Glasgow, 2008. Includes bibliographical references. Print version also available.

Thesis (Ph. D.)--University of Chicago, Dept. of Radiology, August 2000. / Includes bibliographical references. Also available on the Internet.

M. Tech. Civil Engineering / Asphalt mixes are commonly used for paving roads around the world. They consist of mainly bitumen and aggregate materials, which may differ depending on the type of asphalt mix. The shape properties of aggregate particles relevant for the performance of asphalt mixes include the form, angularity and surface texture. There are concerns about the standard test methods used to quantify the shape properties (i.e. angularity, surface roughness, flatness, elongation and sphericity) of aggregates used for road pavement design and construction. These test methods have been reported as time and labour intensive, and have several limitations including human error, lack of accuracy, and repeatability of test results. Although results obtained from these tests have been linked to performance, however these links are questionable. Recently, various researchers and practitioners have indicated that advanced and automated approaches such as imaging and laser scanning techniques would better quantify the shape and surface properties of aggregates. For instance, researchers at the Council for Scientific and Industrial Research (CSIR) found that a portable three-dimensional (3-D) laser scanning system can be used to accurately quantify the shape properties of aggregate particles that are relevant to the performance of asphalt mixes. The overall objective of this study was to use a 3-D laser scanning technique to quantify the shape properties of aggregate materials and relate them to performance of laboratory compacted asphalt mixes.

published_or_final_version / abstract / Computer Science / Master / Master of Philosophy

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Obstetrics and Gynaecology / Doctoral / Doctor of Philosophy

This dissertation presents the results of an investigation into the performance characteristics of a unique hemispherical SPECT (single-photon emission computed tomography) imaging system capable of producing three-dimensional (3D) tomographic images of the human brain. The system is completely stationary and collects all necessary views of the patient simultaneously, with no system motion. The imager consists of twenty small (10cm x 10cm crystal area), digital gamma cameras arranged in a hemispherical pattern around the patient's head and a hemispherical lead aperture. The hemispherical aperture is positioned between the cameras and the head and contains a large number of pinholes; in this way each camera sees a number of overlapping pinhole projections of the radioactive distribution within the patient's brain. The initial investigation of the performance characteristics of a 3D SPECT system of this design were carried out using a computer simulation in which effects due to radiometry, finite pinhole size, finite detector resolution, photon noise, and object attenuation were included. We used a digital 3D brain phantom as the test object and an iterative search algorithm to perform the reconstructions. The simulations were used to compare the performance of a variety of system configurations. Based upon the results of the simulation study, we constructed a laboratory prototype of the 3D SPECT system, which we used to further characterize the expected performance of a clinical imaging system of the same design. Prior to collecting SPECT data we calibrated the imaging system, which required that we efficiently measure and store the spatially variant system response function. These calibration data were then included in the reconstructions of the SPECT phantoms that we imaged. A number of different SPECT phantoms were imaged to demonstrate the system performance. We measured a reconstructed spatial resolution of 4.8mm full-width at half-maximum and a full-system sensitivity of 36cps/μCi, where both values were measured for a point source in air located at the center of the field of view. We also describe an analysis that we performed to determine the equivalent, non-multiplexed system sensitivity; using this method, we found that the equivalent sensitivity was 79% of the measured value for the system configuration and the particular task that we investigated.

Approved for public release, distribution unlimited / With the unveiling of ForceNet, the Navy's architectural framework for how naval warfare is to be conducted in the information age, much of the technological focus has been placed on Web technology. One of the most promising technologies is Web services. Web services provide for a standard way to move and share data more reliably, securely, and quickly. The capabilities imbedded in Extensible Markup Language (XML) and Simple Object Access Protocol (SOAP) can merge previously disparate systems into one integrated environment. Already proven successful in the administrative realm, wide-area networks such as the Secure Internet Protocol Network (SIPRNET) have become secure and reliable enough to pass data between systems and units to support tactical operations. The Modeling, Virtual Environments and Simulation (MOVES) Institute at the Naval Postgraduate School is currently working to extend these precepts into the modeling and simulation world under the Extensible Modeling and Simulation Framework (XMSF) project. By leveraging existing Web service technology, warfighters at the "tip of the spear" can have access to previously unrealized amounts of tactically-relevant data, analysis, and planning tools. The goal of this thesis is to apply the XMSF and Extensible 3D (X3D) graphics to the field of sonar visualization. Undersea warfare is a complex operation that requires a continuous and detailed analysis of the acoustic environment. Tactical sensor employment without a firm understanding of the complete undersea picture can lead to fatal consequences. The Navy has spent significant resources to develop training systems and tactical decision aids in an effort to integrate training, rehearsal and execution. Unfortunately, many of the high-resolution analysis tools that can provide high-resolution sonar prediction results are not easily accessible to the fleet. By taking advantage of Web services and XMSF technology, warfighters will need only access to the network to be able to pull real-time environmental analysis data from large databases, remotely run sonar prediction models on supercomputers, and view detailed three-dimensional (3D) virtual worlds that visualize the undersea picture.

Approved for public release; distribution is unlimited. / Inverse Synthetic Aperture Radar (ISAR) provides full range detection and classification of sea and air based targets through two-dimensional range-Doppler imaging. The Naval Postgraduate School has developed a custom integrated circuit that can simulate false ISAR images in order to fool enemy ISAR platforms. To validate specific hardware choices within this design, this thesis explores the effect on image quality of an overflow occurring within the final 16-bit summation adder of this circuit. Three solutions to the problem of overflows are presented and analyzed. The logical extension of ISAR development, that of three-dimensional target imaging, is next presented through the discussion of 3D monopulse radar, 3D interferometric ISAR, and a 3D, three receiver ISAR. The relative strengths of each approach are compared, along with both MATLAB and X3D software models created for one specific 3D ISAR implementation. Through the superposition of 2D ISAR images it is shown how 3D ISAR images may be created. Moreover, emphasis is placed on using this knowledge to both enhance current 2D ISAR techniques and to modify the false-target chip to handle 3D ISAR return signals. The thesis concludes with a study of Non-Uniform Rational B-Splines, through which the X3D software model was created. / Ensign, United States Naval Reserve