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QC 351 A7 no. 82 / The object of this study was to determine the utility of polarization -discrimination techniques for active optical processing. A baseline of static performance must be established before these techniques can be applied to real -time processing. The theoretical foundation for an alternative to the Vander Lugt technique of re- cording complex spatial filters had been laid by Marathay in 1969. On the basis of his theory, a photosensitive Vectograph TM technique was investigated, in which the image is produced as a polarization pattern rather than as the silver grain image of conventional photography. (1) Photographic characteristics of sensitized Vectographs were determined. The resolution ( >700 1p /mm) and the gray scale achieved indicate that the Vectograph material can also be used for recording Vander Lugt filters. (2) Theoretical analysis showed that the technique can be used to image and process objects in the same system without removal of the filter. It can also be used to generate halfwave plates for the pupil functions described by Toraldo di Francia for superresolution. (3) The Vectograph can perform addition and subtraction of functions recorded on it; it also is suitable for recording real -bipolar filter functions. (4) Variable- contrast images can be recorded. A variable-contrast Vectograph tar- get (VCVT), developed for optical testing, can not only vary the contrast of the recorded image but also reverse its contrast. In a similar fashion, a spatially variable birefringent filter (SVBF) was developed that permits spatial control of the wave- length of the transmitted light. Static and dynamic electro-optical properties of liquid crystal mixtures of cholesteryl-chloride, cholesteryl-nonanoate, and cholesteryl-oleyl-carbonate were studied to determine their feasibility as the modulator in a proposed photoconductor-liquid crystal sandwich, which would be used as a reversible recording medium. (1) Previous research had indicated that cholesteric liquid crystals are circularly dichroic in a narrow wavelength band. The present work showed that light transmitted within this band is actually elliptically polarized. The degree of ellipticity depends on the relationship between the probing wavelength and the wavelength at which the sample becomes circularly dichroic. Outside this narrow wavelength band, the crystals exhibited pure optical activity. (2) The dynamic electro-optical properties of the cholesteric trimixture were measured. An alternating electric field applied parallel to the helical axis of the liquid crystals resulted in a hysteresis in the electro-optical rotatory power of the crystals. The magnitude of the hysteresis would limit cycling of these liquid crystals to a maximum frequency of ^0.10 Hz. (3) A bias voltage applied to the crystals in an attempt to improve the frequency response resulted in a field- induced memory. When the bias voltage was maintained, the optical rotatory power failed to stabilize. Prolonged exposure to the bias voltage severely diminished the electro-optical rotatory power of the crystals.

Thesis (M.B.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / 2031-01-01

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, April 1994. / This project report describes the development of a high speed data acquisition and processing system (DAPS) for an experimental monopulse tracking radar at the Division of Manufacturing and Aeronautical Systems Technology (Aerotek), of CSIR. The system development involved replacement of existing data acquisition hardware and software with an enhanced, PC based, integrated high speed data acquisition system. The system is used for radar acceptance testing, radar monitoring during trials and capture of large volumes of data for off-line processing to pursue research into the phenomenology of radar cross section. The work performed during the execution of this project represents an effort in three technology areas. These are Digital hardware design of custom interface hardware for the ISA bus as implemented on most PC's. This was not a major aim of the project, but was required in the absence of suitable hardware. Formal software specification and design using the real time extensions of Hatley and Pirbhai to the Yourdon and de Marco data flow analysis methodology. The existing software had not been designed using any formal method, and suffered a lack of documentation throughout all phases of the development. The way this project was undertaken has served as an exercise in following the approach, which resulted in a product which is better documented and more maintainable. There are elements of total quality management that are still missing though. • Quality management during software development. At the time of commencement of the project there was no formal commitment to software quality management at Aerotek. Commitment to IS09000 accreditation in future has required that a solid quality ethic and management system be instituted. Current software development follows this approach. A discussion of the topic appears in the conclusion. The DAPS has been in use for approximately two years now. With continued minor modification to meet new user requirements, it has successfully enhanced the usability of the radar system during trials and measurements with the SAAF. / MT2017

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Two aspects of the computer simulation of minerals processing systems were investigated in order to facilitate more effective use of simulation technology. A user-interface was designed and combined with an existing simulator executive, resulting in the implementation of a user-friendly microcomputer based minerals processing simulator, MicroSim. Ease of use was achieved by consideration of the needs of the user of such a program. This resulted in the use of graphical methods for information input and output. Efficient form-filling techniques were developed for numerical data entry and editing. Models for the carbon-in-pulp adsorption process and for continuous gold leaching were derived. The CIP models were derived using a population balance approach. The method of characteristics and the method of moments were found to be particularly useful in solving the resulting equations. Besides being important processes in themselves, the integration of these models into MicroSim provided valuable experience regarding the use of such models in a simulator. / AC 2016

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. June 2017, Johannesburg / As sequencing and genotyping technologies are advancing, larger and more complex sets of biological data are being produced. Databases can be used to efficiently store and manage the data. Typically, publicly available datasets are accessed through web browsers that offer a user-friendly interface to a database, making complex queries simple to execute. However, research projectspecific data are not commonly stored in this way. In this research, a database (designed in MySQL) and accompanying interface (developed using PHP, HTML and CSS) has been designed for the storage and querying of the quality controlled data from the current project using Metabochip-genotyped Birth to Twenty (Bt20) cohort participants and their female caregivers. Users can easily access the data to generate summary statistics on the phenotype data and download phenotype, single nucleotide polymorphism (SNP) annotation and association analysis data that match user-supplied criteria. Some of the data from the database was used to investigate the genetics of blood pressure (BP) in black South African individuals. Hypertension is a major risk factor for cardiovascular diseases (CVDs). BP variation is known to have a genetic component, but genetic studies in indigenous Africans have been limited. Association analysis, carried out in a merged sample of caregivers and participants, pointed to novel regions of interest in the NOS1AP (DBP and SBP), MYRF (SBP) and POC1B (SBP) genes and two intergenic regions (DACH1|LOC440145 (DBP and SBP) and INTS10|LPL (SBP)). Two SNPs in the MYRF gene met the calculated “array-wide” significance threshold (p<6.7x10-7 for the merged dataset) for multiple testing. Genotype imputation is a useful addition to association studies to increase the SNP panel for association testing. An investigation into the efficiency of imputation in this dataset using a mixed population reference panel was carried out. Imputation was achieved with high confidence in all genes, but a more detailed view of the region was only seen in NOS1AP (DBP and SBP in both the merged and female caregiver datasets) and POC1B (Bt20 participant dataset only). Overall, the research contributed a useful tool for the efficient management of project-specific biological data. The analysis and genotype imputation, which is a promising tool in future studies in this or other African datasets, also provided some insight into the genetics of blood pressure in black South Africans with further functional and replication studies in larger samples required to confirm and explain the findings. / MT 2017

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