This thesis is concerned with the extraction of dense three-dimensional depth maps from sequences of two-dimensional greyscale images using correlation based matching. In particular the thesis is focused on the noise processes that occur in the depth map and the removal of that noise using nonlinear filters based on fuzzy systems. The depth from stereo algorithm is reviewed and a widely used correlation based matcher, the Sum Squared Difference (SSD) matcher, is introduced together with an established method of measuring sub-pixel disparities in stereo pairs of images. The noise in the disparity map associated with this matcher is investigated. The conjecture is made that a fuzzy inferencing system can be trained to perform a nonlinear filtering process which is more effective than conventional filters at removing the mixed impulsive and Gaussian-like noise present in the depth map. Six methods of training fuzzy systems of the Sugeno type based on the simulated annealing algorithm are proposed and tested by training fuzzy systems to approximate a simple function of two variables The thesis reviews existing fuzzy logic based filters and proposes a taxonomy for such systems. This distinguishes between direct and indirect acting fuzzy filters. An indirect acting fuzzy filter is applied to the task of smoothing a disparity map. The first order Sugeno fuzzy system is then proposed as an architecture that would be suitable as the basis for a direct acting fuzzy filter. This architecture is then applied to the task of smoothing depth maps derived from real and simulated data. The main contributions of the thesis are the identification of the Sugeno fuzzy system as a form of filter, the proposed training techniques, and the application of fuzzy filters to depth map smoothing.

This thesis addresses itself to the solution of a number of problems which arise in the development of Radio Frequency filters, particularly those involving coupled transmission lines as resonant elements. The text is divided into a number of sections dealing with individual topics. After a brief description of Darlington filter design principles, there is an account of the pivotal role of quarter wave sections and their vital part in the realisation of high frequency filters. This is followed by the development of new material relating to equivalent circuits of physical lines in terms of quarter wave sections, and its application to improvements in the design of wide-band filters. There follows an account of a new procedure for calculating the dimensions of comb-line and inter-digital filters. This section includes a new proposal for the inversion of Getsinger's procedure to permit the calculation of rectangular rod dimensions and spacings from given electrical data. There is also an algorithm for use with round rods which circumvents the tedious manual interpolation procedure devised by Cristal. There follows an investigation of and a proposed solution to a long-known but unexplained discrepancy existing between the calculated and measured pass-band width of the class of comb-line filters. With the new procedure the discrepancy reported previously to be of the order of 10% is eliminated. Finally, experimental evidence is adduced to verify the algorithms outlined in the preceding chapters.

Progress in integrating microwave circuits depends largely on the development of computationally effective and accurate numerical methods. These methods allow a miniaturization of microwave components and their utilization at higher frequency. In this thesis, the application of the mode matching method is described as well as their modification to different kinds of structure in rectangular and circular waveguides. The task is to design and optimize filters, multiplexers and impedance matching networks. In its most general form, the mode matching method at waveguide discontinuities requires the matching of four field components. However, to improve computational efficiency, the effect of matching only two field components (versus four field components) is investigated and successfully exploited for selected discontinuities. To satisfy space requirements, low loss, compact, and lightweight diplexer, triplexer and quadriplexer structures in rectangular waveguide technology are designed and optimized. The analysis is made possible by decomposing the structure into simple discontinuity sections such as discontinuity in width, height or bi- and tri-furcations. Three different types of discontinuities in coaxial waveguide are investigated: the outer step, the inner step and the gap discontinuities. By cascading such discontinuities, filters or matching networks can be obtained. Finally, a new type of circular waveguide bandpass filter using printed metal inserts is developed and designed in Ka-band. A comparison between theoretical results and measurements shows excellent agreement. / Graduate

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Most eye drops are dispensed in multi-dose containers, hence protection should be given against microbial contamination during use. To remain sterile during it's use, the solution should contain a preservative in such concentration so that it kills micro-organisms in a short time. It has been stated in the literature that the instillation of contaminated eye drops constitutes a greater danger than the intravenous injection of a contaminated solution since the cornea is nonvascular and lacks the normal antimicrobial defences of the blood stream. Amongst the preservatives used, those included in the official formulations for eye drops are Chlorhexidine Acetate, Phenyl Mercuric Nitrate, Benzalkonium Chloride, and to some extent Phenylethanol, which may be used in combination with Benzalkonium Chloride. The main purpose of this investigation has been to determine the adsorption of these preservatives by different filters during sterilization by filtration. Part 1, p. 2.

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The notion of a filter F ∈ 2²x has been extended to that of a : prefilter: ƒ ∈ 1²x, generalised filter ƒ ∈ 2²x x and fuzzy filter ᵩ ∈ 1¹x. A uniformity is a filter with some other conditions and the notion of a uniformity D ∈ 2²xxx has been extended to that of a : fuzzy uniformity d ∈ 1²xxx , generalised uniformity ∈ 1²xxx and super uniformity b ∈ 1¹x. We establish categorical embeddings from the category of uniform spaces into the categories of fuzzy uniform spaces, generalised uniform spaces and super uniform spaces and also categorical embeddings into the category of super uniform spaces from the categories of fuzzy uniform spaces and generalised uniform spaces.

The advent of the integration of discrete passive components is a direct result of the drive towards the minimisation of power electronic converters and filters. To this end Integrated Power Passive Modules (IPPMs) have been utilised in the past. The IPPMs discussed in this dissertation refer to structures consisting of dielectric layers sandwiched between layers of conductive material. The use of these types of structures in various applications has been well documented. However, the applications have been single-phase in nature and the exact configuration of the IPPMs has been largely dependent on the designers’ past experience with the modules. The development of a synthesis procedure to identify the required configuration for any particular application would be of great benefit to designers. The foundation of such a synthesis procedure was laid through an exhaustive search of all possible configurations that can be realised with a three conductive layer IPPM. From this exhaustive search a number of general trends, between the configurations and their associated frequency response, were observed. Furthermore, a number of principles underlying the functionality of the configurations were highlighted during the course of the exhaustive search. The validity of some of these results was experimentally investigated through the design and implementation of an integrated EMI filter. The EMI filter considered in this study differed from integrated EMI filters, previously reported on, through the fact that the filter considered herein was to be implemented in a three-phase application. To this end a set of configurations that realise low pass filters were identified from the results of the exhaustive search. The application of these configurations was expanded from single-phase to three-phase by mapping the configurations onto a building block component used to realise the three-phase application. Simulations of these three-phase filters were used to analyse the filter performance. From this analysis a subset of configurations were identified as displaying the best performance characteristics. The configurations within this subset were further analysed using the results of the exhaustive search. In so doing two configurations were isolated for use in a practical realisation of the three-phase filters. The physical design and construction of the integrated three-phase filters, as well as the test bench, was considered. The performance of the filters was investigated through comparative measurements of common mode and differential mode currents, in the test bench, in the presence and absence of the filters. From this investigation significant reduction in the conducted EMI noise was seen through the introduction of the filters into the system. / Dr. I. W. Hofsajer