Architectural research for Field-Programmable Gate Arrays (FPGAs) tends to use an experimental approach. The benchmark circuits are used not only to compare different architectures, but also to ensure that the FPGA is sufficiently flexible to implement the desired variety of circuits. The most common benchmark circuits used for architectural research are circuits from the Microelectronics Center of North Carolina (MCNC). These circuits are small; they occupy less than 3% [5] of the largest available commercial FPGA. Moreover, these circuits are more representative of the glue logic circuits that were targets of early devices. This contrasts with the trend towards implementing Systems on Chip (SoCs) on FPGAs where several functional modules are integrated into a single circuit which is mapped onto one device. In this thesis, we develop a synthetic system-level circuit generator that connects pre-existing circuits in a realistic manner to build large netlists that share the characteristics of real SoC circuits. This generator is based on a survey of contemporary circuit designs from industrial and academic sources. We demonstrate that these system-level circuits scale well and that their post-routing characteristics match the results of large pre-existing benchmarks better than the results of circuits from previous synthetic generators. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Using complexing-agent assisted sol-gel routes, mixed Pd/ceria-alumina and Pd/terbia-ceria-alumina catalysts were prepared. The materials have been characterised by means of ICP-MS, TEM, EDX, XPS, XRD, BET, TPR, TPO and TPD. Catalytic testing was carried out in a temperature programmed mode as well as isothermally, using synthetic exhaust gas mixtures with different air-to-fuel ratios. The obtained results were compared with those of traditionally impregnated Pd/ceria-alumina and PtRh/ceria-alumina. Evaluating the catalysts potential as three-way converters, it has been shown that as a result of the sol-gel preparation chosen, highly homogeneous materials were produced. These had (i) much higher oxygen storage potential (especially at low temperatures, T ≈ 400 - 500K), (ii) improved metal support interactions and (iii) lower CO and propane light-off temperatures (T50%(CO) ≈ 423K, T50%(C3H8) ≈ 593K for R ≥ 1). Under fuel-rich conditions an improved low temperature NO activity was shown for the ceria-containing materials. This was attributed to a ceria-mediated redox mechanism and an improved Pd-ceria interaction for these sol-gel-derived samples. The addition of terbia was found to promote the catalysts propane activity, especially under fuel-rich conditions. The application of the different catalysts as three-way converters has been discussed, with special emphasis on their potential during the cold-start period. In a further set of catalytic experiments, using less complex gas mixtures, a more comprehensive view of the detailed Pd chemistry involved in these new three-way catalysts was obtained.

Synthetic speech is a valuable means of output, in a range of application contexts, for people with visual, cognitive, or other impairments or for situations were other means are not practicable. Noise and reverberation occur in many of these application contexts and are known to have devastating effects on the intelligibility of natural speech, yet very little was known about the effects on synthetic speech based on unit selection or hidden Markov models. In this thesis, we put forward an approach for assessing the intelligibility of synthetic and natural speech in noise, reverberation, or a combination of the two. The approach uses an experimental methodology consisting of Amazon Mechanical Turk, Matrix sentences, and noises that approximate the real-world, evaluated with generalized linear mixed models. The experimental methodologies were assessed against their traditional counterparts and were found to provide a number of additional benefits, whilst maintaining equivalent measures of relative performance. Subsequent experiments were carried out to establish the efficacy of the approach in measuring intelligibility in noise and then reverberation. Finally, the approach was applied to natural speech and the two synthetic speech systems in combinations of noise and reverberation. We have examine and report on the intelligibility of current synthesis systems in real-life noises and reverberation using techniques that bridge the gap between the audiology and speech synthesis communities and using Amazon Mechanical Turk. In the process, we establish Amazon Mechanical Turk and Matrix sentences as valuable tools in the assessment of synthetic speech intelligibility.

Please read the abstract in the section 00front of this document Copyright 2000, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bisschoff, J 2000, Oxygenated hydrocarbon compounds as flame retardants for polyester fabric, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-01122007-112752 / > H 81/th / Dissertation (M Eng (Chemical Engineering))--University of Pretoria, 2007. / Chemical Engineering / unrestricted

The Gujarat earthquake of 2001 caused widespread devastation to livelihoods and the built environment, demolishing or badly damaging in excess of 400,000 buildings in the Kutch region as well as killing upwards of 15,000 people. This research examines the work of Hunnarsh?l?, an urban development and architecture firm based in Bhuj, Gujarat, India who, in response to the immediate and long-term needs apparent in the aftermath of the earthquake, proposed an owner-driven redevelopment strategy which sought to promote the socio-cultural needs of the ‘users’ as embodied in the artefacts and processes of the vernacular traditions common to the communities, as essentially empowering and therefore critical to the long-term sustainability of any reconstruction work. Hunnarsh?l?’s approach is an illustration of the coproduction of housing, leading to what is termed here as ‘synthetic vernacular architecture’. The thesis explores the potential of the coproduction of housing as an alternative model for architectural development for disadvantaged individuals and groups, with the potential for broader application in other contexts. Using three settlements on which Hunnarsh?l? worked as case studies, this research examines the efficacy of such an approach through both artefacts and processes of production as found in the field through a qualitative methodological approach based on ethnographic and design analysis methods. The research indicates that whilst there are distinct and problematic issues raised by an approach such as that used by Hunnarsh?l? in the context of Kutch, their approach is an illustration of the coproduction of housing, Such an approach has not been investigated to any significant degree in terms of its potential as a means of making culturally resonant architecture and therefore as a strategy of empowerment. This it is felt is an oversight which this research seeks to remedy.

Electrospinning is a technique, which can be used to produce nanofibrous materials by introducing electrostatic fields into the polymer solution. Due to their intrinsic properties, such as small fiber diameter, small pore size and large surface area, nanofibres are suitable for use in a variety of applications including wound dressing, filtration, composites and tissue engineering. The study demonstrates the successful and optimised production of Poly(ethylene oxide) (PEO) and chitosan nanofibres by electrospinning. The biocidal effects of chitosan, chitosan-silver nanofibres and silver nanoparticles were successfully investigated. To set up a functional electrospinning apparatus, the PEO solution parameters (concentration, molecular weight, solvent, and addition of polyelectrolyte) and applied potential voltage on the structural morphology and diameter of PEO nanofibres were studied. At lower PEO concentrations, the fibres had morphology with a large variation in fibre diameter, whereas at the higher concentrations, the nanofibres exhibited ordinary morphology with uniform but larger fibre diameters. Higher molecular weight showed larger average diameters when compared to that obtained with the same polymer but of a lower molecular weight. The addition of polyelectrolyte to the polymer solution had an influence on the structural morphology of the PEO. Flow simulation studies of an electrically charged polymer solution showed that an increase in the flow rate was associated with an increase in poly(allylamine hydrochloride) (PAH) concentration for the low molecular weight polymer, the shape and size of the Taylor cone increasing with an increase in PAH concentration for the low molecular weight polymer. During optimization of the PEO nanofibres, based on statistical modelling and using the Box and Behnken factorial design, the interaction effect between PAH concentration and the tip-to-collector distance played the most significant role in obtaining uniform diameter of nanofibres, followed by the interaction between the tip-to-collector distance and the applied voltage and lastly by the applied voltage. The production and optimization of chitosan nanofibres indicated that the interactions between electric field strength and the ratio of trifluoroacetic acid (TFA) and dichloromethane (DCM), TFA/DCM solvents as well as between electric field strength and chitosan concentration had the most significant effect, followed by the concentration of chitosan in terms of producing nanofibres with uniform diameters. Chitosan and chitosan-silver nanofibres could be successfully electrospun by controlling the solution properties, such as surface tension and electrical conductivity with the silver nanoparticles in the chitosan solutions affecting the electrospinnability. The silver nanoparticles in the chitosan solution modified the morphological characteristics of the electrospun nanofibres, while the conductivity and the surface tension were elevated. The fibre diameter of the chitosan and chitosan-silver nanoparticles decreased with an increase in the silver content. The electrospun chitosan nanofibres had a smooth surface and round shape as compared to the silver-chitosan nanofibres with a distorted morphology. The chitosan and chitosan-silver nanofibres as well as the silver nanoparticles exhibited antimicrobial or inhibition activity against S. aureus than against E. coli. S. aureus bacterial culture showed good cell adhesion and spreading inwards into the chitosan nanofibrous membrane. The chitosan-silver nanofibres exhibited a greater minimum inhibitory concentration (MIC), followed by silver nanoparticles and then chitosan nanofibres; suggesting a synergistic effect between the chitosan and silver nanoparticles.

Flow chemistry and continuous processing techniques are now frequently used in synthetic laboratories, taking advantage of the ability to contain reactive or hazardous intermediates and to perform moderate scale-up processes for important compounds. However, only a limited number of methods and tools for connecting flow synthesis steps into a single protocol have been described, and as a result manual interventions are frequently required between consecutive stages. There are two main challenges to overcome. Work-up operations such as solvent extractions and filtrations are invariably needed to ensure high purity of the intermediates. Solutions for achieving this are well established within industrial facilities for continuous production, but adapting such machinery for laboratory use is rarely straightforward. Secondly, the combination of multiple steps tends to result in a more elaborate reactor configuration. The control procedures required to achieve optimum performance may then be beyond the capabilities of a single researcher. Computer control and remote monitoring can help to make such experiments more practical; but commercially-available systems are often highly specialised, and purpose-built at high cost for a particular system, and so are not suitable for laboratory scientists to use routinely. This work describes the development of software tools to enable rapid prototyping of control systems that can integrate multiple instruments and devices (in Chapter 2). These are applied to three multi-step synthesis projects, which also make use of enabling technologies such as heterogeneous reagents and in-line work-up techniques so that material can be passed directly from one stage to the next: In Chapter 1, a series of analogues of a precursor to imatinib, a tyrosine kinase inhibitor used for the treatment of chronic myeloid leukaemia, are prepared. A “catch-react-release” technique for solid-phase synthesis is used, with computer-controlled operation of the reactors. In Chapter 3, a two-step procedure for the synthesis of piperazine-2-carboxamide, a valuable 3D building block, is developed. A computer control system enabled extended running and the integration of several machines to perform optimisation experiments. In Chapter 4, improvements to the continuous synthesis of 2-aminoadamantane-2-carboxylic acid are discussed. This includes an integrated sequence of three reactions and three workup operations. The final chapter describes a project to evaluate the application of control techniques to a medicinal chemistry project. New ligands for BRD9 and CECR2, proteins involved in the recognition of acetylated histone proteins, are produced. A number of triazolopyridazine compounds were synthesised and tested using a number of assay techniques, including a frontal-affinity chromatography system under development within our group. Pleasingly, the qualitative FAC data showed a good correlation with biological assessments made using established assay techniques. Further work using the FAC method is ongoing.

Life, as we know it, has emerged from the association of simple building blocks (e.g. HCN, NH3, aldehydes, etc). The reactions required to form the complex subunits of life face a great entropic barrier due to the intermolecular nature of their reactivity. Intermolecular reactions are slow at low concentrations, and therefore, the assembly of complex subunits requires the presence of a concentration mechanism. Formaldehyde, which was present in concentrations as high as 0.02 M, may have been used as a concentration mechanism on early Earth. By tethering two molecules together, formaldehyde allows catalysis via temporary intramolecularity. Moreover, formaldehyde has been shown to act as a hydrolase / hydratase mimic, allowing important rate accelerations in hydration and hydrolysis reactions which are of fundamental importance to prebiotic chemistry. Herein, the efficiency of formaldehyde as a catalyst, operating via temporary intramolecularity is demonstrated for a hydroamination reaction that occurs in dilute aqueous conditions. First, using soluble N-methylallylamine and Nmethylhydroxylamine, formaldehyde allowed catalytic turnover at prebiotically relevant formaldehyde concentrations (0.02 M) for a model hydroamination reaction. The efficiency of formaldehyde was compared to other prebiotic aldehydes, demonstrating that although other prebiotic aldehydes are capable of inducing temporary intramolecularity, they were inferior.A second small molecule which may have played a role in the origin of life is D-glyceraldehyde. Since life’s molecules are homochiral, there is a need to explain how this homochirality arose. There have been many breakthroughs by the scientific community when it comes to addressing this challenge, however there is still no general consensus on the origins of homochirality from a prebiotic perspective. Herein, we demonstrate that D-glyceraldehyde is capable of templating a challenging intermolecular reaction while also transmitting some of its chirality to the product. Though the enantiomeric excess produced was generally low (usually around 20 %), there is a significance behind these results due to prebiotically relevant amplification procedures. Lastly, formaldehyde is examined as a possible desymmetrizing agent; coupled with Brønsted acids, the possibility of formaldehyde to induce desymmetrization of alpha-amino or alpha-hydroxy diesters to produce azlactones, and oxalactones, respectively will be established. Moreover, the use of a chiral Brønsted acid would introduce the ability to achieve this transformation in an enantioselective manner. The resulting azlactones / oxalactones are valuable for two reasons: 1) the lactones are present in bioactive molecules, and 2) the lactones can be hydrolyzed to produce chiral alpha-amino / alpha-hydroxy acids. Therefore, we began a systematic study of the conditions required to allow this transformation to occur. This study indicates that the desymmetrization of an alpha-amino diester is possible, producing moderate yields of the resulting azlactone. The desymmetrization of alpha-hydroxy diesters however proved more challenging, and no conversion was observed. Further investigation is required to the increase efficiency of the desymmetrizations, and experimentation with chiral Brønsted acids is required in order to discover enantioselective transformations.

In order to increase results accuracy and to provide some time-dependency to CFD results, embedded RANS/LES simulations are getting more and more interesting. In order to run these simulations accurate LES boundary conditions are required, not to affect the downstream results with a poor quality synthetic turbulence generation. Considering the currently developped methodologies, it is not possible to generate a divergence free turbulent flow which satisfy a non isotropic state of turbulence. The author started from the Synthetic Eddy Method (SEM) defined by Jarrin (2009), and defined a new shape function with the ability to satisfy continuity. The new methodology, named Divergence Free SEM (DFSEM), is able to reproduce almost any kind of turbulence anisotropy by using a special shape function and adapting the eddies intensities in order to match the Reynolds stress tensor rather than using the Lund coefficients, as most of the precursor methodologies did. Results comparisons against SEM and some other very popular synthetic turbulence models in some academic cases, proved that a reduce influence on the downstream flow was achieved. In most of the cases the friction coefficient Cf , used as a performance parameter, benefit by reducing the downstream developping zone by almost 50% in most cases, when compared against SEM. Another issue that has been tackled regards the unphysical pressure fluctuations present because of the synthetic turbulence, due to non perfectly constant mass-flow rate imposed in stochastic methodologies. The new methodology also showed an increased flexibility as it has been tested in embedded DDES simulation, by using the blending function to activate/deactivate it, and again it showed improved performances when compared against standard SEM.

The purpose of this paper is to investigate some of the properties of convex sets in the plane through synthetic geometry.