Includes abstract. / Includes bibliographical references. / The Pt[8]Zr ordering transformation in Pt 11 at. % Zr alloys has been studied. The study included determination of the formation of the Pt[8]Zr phase and its order/disorder transformation temperature (Tc). Electron diffraction patterns and dark field images were obtained from transmission electron microscopy to characterize the Pt[8]Zr phase. Microhardness measurements and light microscopy were used to investigate the Pt[8]Zr ordered phase and its effects on hardness and microstructure respectively. The Pt[8]Zr ordered phase was found to be present in the initial as-cast condition and in specimens heat treated up to a temperature of 1070 °C. This is consistent with the DSC measurements of Tc, determined to be 1068 °C. The nucleation of the ordered phase was found to be rapid at any temperature below Tc but the growth of this ordered phase was rather slow, probably due to inadequate vacancies present in the alloy. The domain size of the Pt[8]Zr phase was found to be approximately 10 nm for specimens heat treated at 1000 °C for up to 600 hours.

Includes bibliographical references. / The aim of this thesis was to investigate the thermodynamics and the kinetics of the stripping of palladium from a typical palladium organic. The thesis firstly characterizes the thermodynamic effects of temperature and strip acid normality on the stripping of palladium and secondly investigates the kinetics of the palladium stripping reaction by exploring the effect of impeller speed and type on the overall volumetric mass transfer coefficient. which was the major focus of this thesis.

Includes abstract. / Includes bibliographical references. / Rural-urban migrations have contributed to the steady increase in the population of Cape Town. Many of the migrants have settled in informal settlements because they cannot afford to rent or buy decent housing. Many of these settlements are however located on marginal and often poorly drained land. Consequently, most of these settlements are prone to flooding after prolonged rainfall. Current flood risk management techniques implemented by the authorities of the Cape Town City Council (CTCC) are ideal for formally planned settlements but are not designed to support informal settlements...This study sought to investigate a methodology that the CTCC could use to improve flood risk assessment.

Includes bibliographical references. / The theory of inelastic solids involving thermodynamic potential functions with internal variables is reviewed. Use is made of the condition for stable thermodynamic equilibrium in order to obtain dual minimum principles for the equilibrium state of a solid inelastic body. This leads to dual forms of the incremental (or rate) theorems and their respective extended forms. The extended static incremental theorem is applied to a pin-jointed truss and an algorithm suggested for solution of the ensuing programming problem. Numerical examples are given. A class of bounding theorems is also studied from the point of view of the potential functions. Bounds on the work and complementary work are obtained and properties of the bounding functions examined. Finally, the bound on a functional, which has been used to obtain general work and displacement bounds for dynamically loaded structures, is discussed.

The purpose of this work is to develop an algorithm for use on a small digital computer in the conversational mode. This algorithm to scale and determine the patching configuration for the simulation of any system on an analog computer. Further, this should be in a form suitable for the implementation of automatic patching in a hybrid computer which contains the necessary switching matrix and hardware. The method of solution chosen here relies heavily on modern control theory, and in this lies both its strength and its weakness. The advantage of the method is that it forms a direct link between the State Space representation of a system and the analog computer simulation of that system. The chief disadvantage is that it is cumbersome in the handling of non-linear systems. The method can be divided broadly into two sections: 1) Digital simulation of system in order to determine the maximum values of all variables. 2) Scaling and analog set-up.

South Africa’s Freeway Management System (FMS) in Cape Town has recorded an alarming increase in pedestrian activity on its freeways in recent years, with a similar trend in (fatal) freeway pedestrian crashes. Both South African and international studies have demonstrated the relevant factors that account for the choices of pedestrians to cross roadways, while few studies have looked at freeway crossing. This study was undertaken to identify and estimate the factors that influence illegal freeway crossing using a discrete choice experiment in Cape Town. It is hypothesized that freeway pedestrian crossing is driven by personal factors and the perceived contribution thereof to the risks associated with the crossing using a footbridge or (illegally) at-grade. Using a stated choice survey including a perceived crossing risk assessment to estimate a series of choice models and based on a 300 participants survey, intercepted along three Cape Town freeways, ordered-responses logit models were developed to estimate risk perception thresholds for both general risk perception (prior to the choice experiment) as well as choice – task specific risk perception. Furthermore, basic and mixed logit models were estimated for freeway crossing choice. Correlations between risk perception and the crossing choices using a Cholesky transformation matrix were established. Finally, the implied relative sensitivities, or tradeoffs, between at-grade and footbridge crossing alternatives were estimated. The findings of this study confirm that, as expected, crossing choice is largely influenced by a combination of built environment, vehicular and pedestrian traffic, as well as socio-demographic characteristics. Among the 8 selected factors, traffic, walking distance and law enforcement presence were observed to be most vital in influencing the risk perception of pedestrians. Results show that younger pedestrians were more risk seeking than their older counterparts and that tenure - the length of time that a pedestrian has lived in Cape Town reduces the risk perception levels of traffic safety. Moreover, pedestrians were more likely to cross with the footbridge rather than directly under normal circumstances. As pedestrian safety is a part of policy interventions in transport, this thesis also suggests an approach to solve the problem of illegal freeway crossing. The results of this study can inform opportunities to counter the upward trend of fatalities and provide suggestions for policy-making, interventions and campaigns that would lead to improved freeway crossing safety.

Isogeometric analysis (IGA) is a computational analysis technique that can serve as an alternative to the traditional finite element method (FEM) in approximating solutions to differential equations. IGA is not necessarily more efficient that traditional FEM, but because of its nature, can naturally handle a greater variety of complex geometries. IGA is based on the use of NURBS (non-uniform rational B-splines), mathematical descriptions of geometry which are the standard of representing geometry in computer aided design (CAD) modeling software. IGA therefore links the CAD world to the world of analysis. Traditional FEM was developed before NURBS, in the 1950s and therefore developed quite separately. This project focuses on the fundamentals and implementation of IGA for problems, including one-dimensional, two-dimensional scalar, two-dimensional vector-valued and simple non-linear problems. For each new problem, the underlying mathematics is developed and the implementation is discussed in detail. One of the major contributions of this project is considered to be the detail in which the implementation of the Neumann boundary condition is described. There is none of this level of detail in any of the available literature. All problems solved are demonstrative and was written in a modular way that is easy to read and understand. Furthermore, how to extract NURBS data from CAD software is discussed, which would prove useful for future problems with more complex geometry. While the work done in this project is not considered novel, the thoroughness in which the project was approached is hoped to be useful for future projects. From this project, the work can be expanded to more complex geometries, multi-patch problems with the help of CAD programs or more complex non-linear problems.

Vehicle safety remains an important topic in the automotive industry due to the large number of vehicle accidents each year. One of the causes of vehicle accidents is due to vehicle instability phenomena. Vehicle instability can occur due to unexpected road profile changes, during full braking, obstacle avoidance or severe manoeuvring. Three main instability phenomena can be distinguished: the yaw-rate instability, the rollover and the jack-knife phenomenon. The main goal of this study is to develop a yaw-rate and rollover stability controller of an Autonomous Scaled Ground Vehicle (ASGV) using Nonlinear Model Predictive Control (NMPC). Open Source Software (OSS) known as Automatic Control and Dynamic Optimisation (ACADO) is used to design and simulate the NMPC controller based on an eight Degree of Freedom (8 DOF) nonlinear vehicle model with Pacejka tire model. Vehicle stability limit were determined using load transfer ratio (LTR). Double lane change (DLC) steering manoeuvres were used to calculate the LTR. The simulation results show that the designed NMPC controller is able to track a given trajectory while preventing the vehicle from rolling over and spinning out by respecting given constraints. A maximum trajectory tracking error of 0.1 meters (on average) is reported. To test robustness of the designed NMPC controller to model mismatch, four simulation scenarios are done. Simulation results show that the controller is robust to model mismatch. To test disturbance rejection capability of the controller, two simulations are performed, with pulse disturbances of 0.02 radians and 0.05 radians. Simulations results show that the controller is able to reject the 0.02 radians disturbance. The controller is not able to reject the 0.05 radians disturbance.

Electrochemical Impedance Spectroscopy (EIS) has been largely employed for the study of reaction kinetics and condition monitoring of batteries during different operational conditions, such as: Temperature, State of Charge (SoC) and State of Health (SoH) etc. The EIS plot translates to the impedance profile of a battery and is fitted to an Equivalent Electric Circuit (EEC) that model the physicochemical processes occurring in the batteries. To precisely monitor the condition of the batteries, Kramers-Kronig relation: linearity, stability and causality as well as the appropriate perturbation amplitude applied during EIS should be adhered to. Regardless of the accuracy of EIS, its lengthy acquisition time makes it impracticable for online measurement. Different broadband signals have been proposed in literature to shorten EIS measurement time, with different researchers favouring one technique over the other. Nonetheless, broadband signals applied to characterize a battery must be reasonably accurate, with little effect on the systems instrumentation. The major objective of this study is to explore the differences in the internal chemistries of the lithium-ion and lead acid batteries and to reduce the time associated with their condition monitoring using EIS. In this regard, this study firstly queries the methodology for EIS experiments, by investigating the optimum perturbation amplitude for EIS measurement on both the lead acid and lithium-ion batteries. Secondly, this study utilizes electrochemical equations to predict the dynamics and operational conditions associated with batteries. It also investigates the effect of different operational conditions on the lead acid and lithium-ion batteries after EEC parameters have been extracted from EIS measurements. Furthermore, different broadband excitation techniques for rapid diagnostics are explored. An online condition monitoring system is implemented through the utilization of a DC-DC converter that is used to interface the battery with the load. The online system is applied alongside the different broadband signals. The deviation in the broadband impedance spectroscopy result is compared against the Frequency Response Analyzer (FRA) to determine the most suitable technique for battery state estimation. Based on the comparisons, the adoption of a novel technique – Chirp Broadband Signal Excitation (CBSE) is proposed for online condition monitoring of batteries, as it has the advantage of being faster and precise at the most important frequency decade of the impedance spectrum of batteries.

This dissertation is a comparative study of tool-flows for rapid prototyping of SDR DSP operations on programmable hardware platforms. The study is divided into two parts, focusing on high-level tool-flows for implementing SDR DSP operations on FPGA and GPU platforms respectively. In this dissertation, the term ‘tool-flow’ refers to a tool or a chain of tools that facilitate the mapping of an application description specified in a programming language into one or more programmable hardware platforms. High-level tool-flows use different techniques, such as high-level synthesis to allow the designer to specify the application from a high level of abstraction and achieve improved productivity without significant degradation in the design’s performance. SDR is an emerging communications technology that is driven by - among other factors – increasing demands for high-speed, interoperable and versatile communications systems. The key idea in SDR is the need to implement as many as possible of the radio functions that were traditionally defined in fixed hardware, in software on programmable hardware processors instead. The most commonly used processors are based on complex parallel computing architectures in order to support the high-speed processing demands of SDR applications, and they include FPGAs, GPUs and multicore general-purpose processors (GPPs) and DSPs. The architectural complexity of these processors results in a corresponding increase in programming methodologies which however impedes their wider adoption in suitable applications domains, including SDR DSP. In an effort to address this, a plethora of different high-level tool-flows have been developed. Several comparative studies of these tool-flows have been done to help – among other benefits – designers in choosing high-level tools to use. However, there are few studies that focus on SDR DSP operations, and most existing comparative studies are not based on well-defined comparison criteria. The approach implemented in this dissertation is to use a system engineering design process, firstly, to define the qualitative comparison criteria in the form of a specification for an ideal high-level SDR DSP tool-flow and, secondly, to implement a FIR filter case study in each of the tool-flows to enable a quantitative comparison in terms of programming effort and performance. The study considers Migen- and MyHDL-based open-source tool-flows for FPGA targets, and CUDA and Open Computing Language (OpenCL) for GPU targets. The ideal high-level SDR DSP tool-flow specification was defined and used to conduct a comparative study of the tools across three main design categories, which included high-level modelling, verification and implementation. For tool-flows targeting GPU platforms, the FIR case study was implemented using each of the tools; it was compiled, executed on a GPU server consisting of 2 GTX Titan-X GPUs and an Intel Core i7 GPP, and lastly profiled. The tools were moreover compared in terms of programming effort, memory transfers cost and overall operation time. With regard to tool-flows with FPGA targets, the FIR case study was developed by using each tool, and then implemented on a Xilinx 7 FPGA and compared in terms of programming effort, logic utilization and timing performance.