ABSTRACT The different options involved in cam systems design such as types of cams and followers, number of applicable standard cam functions, divisions of follower motion-segments, and possible combinations of follower displacement profiles, among others, were critically studied to determine the structure and capabilities of a software package suited for extensive design analyses. The software was applied in the design of cam profiles with selected follower and cam functions and the result...
ABSTRACT Empirical correlations for Nusselt number (Nu) in a staggered multi-row multi-column cross-flow, tube-type heat exchanger is presented in this paper. In the experiment, air at ambient banks of cylindrical rods arranged in staggered configuration of 5 rows by four columns. A test element consisting of a tube of pure copper with length internal and external diameters of 0.125, 0.0115 and 0.0125 m was heated to a maximum temperature of about 90Oc and inserted into the air stream in the ...
Abstract Abdominal aortic aneurysms affect 0.2% of the population and are closely associated with intraluminal thromboses (ILTs) that develop in the sac. Advanced imaging and treatment techniques are available, however there is room for improvement in the methods used to predict the outcome or necessity of surgical intervention. For a computational model to be useful in this clinical setting, it would need to incorporate relevant patient-specific data and prioritise simplicity and speed over...
Abstract This body of work entailed the broad contrasting of two hydrocarbon fuel auto-ignition models formulated for the emulation of combustion dynamics in Homogeneous Charge Compression Ignition (HCCI) engines. The first (empirical) auto-ignition model was adapted from its previously published form, for HCCI engine model implementation. This model was then combined with an explicit, single zone, thermodynamic engine model in order to investigate combustion phasing control strategies over ...
Abstract This research forms part of an ongoing HCCI study at the SASOL Advanced Fuels Laboratory to investigate and understand engine configuration and fuel chemistry effects on combustion in HCCI engines. This project continues from a previous project where a small Progress Aero Works (PAW) 6.5cc high speed model diesel" aeroplane engine was found to operate in HCCI mode with surprising ease and exibility. A 25cc, four-stroke, single cylinder Honda GX25 engine, possessing 2-valves with an o...
Blast loading of sandwich panels with thin-walled tube cores
Abstract The geomemc deformalion induced by ([0 equal blast loads on uppositt sides of a thin-walled square tube ",ill weaken the siruclure. This will improve i[s energy absorbrioll charanenstics compared to a gcomccrically "perfect" square tube of the same size by reducing me crush load when cOlnpressed i11 the axial direction. Different types of impcrfcnioll can be induced depending on the Sl?e of the blast loads. Consequent to the blast loads, high temperalures ""ill also be induced by a...
ABSTRACT The efficiency of mixing processes in impeller agitated tanks depends highly on the hydrodynamics. Computational fluids dynamics (CFD) provides a method of predicting the complex tlow structures in stirred tanks. As with any approximate numerical method, CFD methods are subject to errors due to assumptions in the underlying mathematical models, as well as errors due to the numerical solution procedures. The aim of this thesis was to present a CFD method that accurately models the hy...
ABSTRACT Continuum and finite element formulations ofthe static and dynamic initial-boundaryvalue evolution (elastoplastic) problems are considered in terms of both the classical and internal variable frameworks. The latter framework is employed to develop algorithms in the form of convex mathematical programming and Newton-Raphson schemes. This latter scheme is shown to be linked to the former in the sense that it expresses the conditions under which the convex non-linear function can be m...
ABSTRACT Several theories of creep and creep rupture are reviewed. Specific attention is devoted to the brittle damage theory proposed by Kachanov. Creep, damage and life predictions for rectangular or circular cross section beams under bending and tensile loads are presented. Comparison with data for a Ni Superalloy showed life predictions could be 30X in excess of experimental values. This beam model also revealed that it is imperative that no bending moments be inadvertently applied during...
ABSTRACT Coal is one of the most importa~t energy resources in South Africa. It covers 80% of the country's energy needs and provides valuable foreign exchange and employment. The purpose of this thesis is to provide an analytical framework for the examination of the demand for coal for the generation of electricity where more than 50% of the coal produced in the country is consumed. More specifically, the aim of the thesis is to identify the factors influencing the demand for steam-coal, dis...
Abstract Selection of optimum machining parameters is an essential factor in process planning for efficient metal cutting operations. In this study, an artificial neural network- based tool wear predictive model and a genetic algorithm-based optimization model were developed to determine the optimum cutting parameters for turning NST 37.2 steel with uncoated carbide cutting inserts. Multi-layer, feed-forare, back -propagation network was used in predictive model, while maximum metal removal r...
ABSTRACT Tool wear measurement is of great concern in machining industry, as it affects the surface qualities, dimensional accuracy and production costs of the machined components. The orthodox methods of measuring tool wear are time consuming and limited in accuracy and application. In this study, machine vision system based on digital image processing was developed for measurement of tool wear. The basic components of the system are: a charge coupled device (CCD) camera, PC, Microsoft Wind...
ABSTRACT Energy benchmarking and carbon footprint reduction opportunities in Portland cement manufacturing processes in Nigeria are presented. Life Cycle Assessment (LCA) is used to estimate the environmental impact of three cement manufacturing processes in Nigeria. The energy consumption of the cement manufacturing processes are evaluated using energy Benchmarking and Energy Savings Tool for cement (BEST-Cement). BEST-Cement evaluates and compares the energy consumption of the cement manuf...
Abstract The Design of an Efficient Solid Waste Management and Disposal Scheduling System in a metropolis is hereby presented. The design employed ten landfill sites in contrast to the existing one landfill site in the metropolis. The metropolis was divided into ten zones and a Hungarian mathematical model was used to get the optimal assignment of the proposed landfill sites to the zones. This model was applied to the field data obtained from the road net-work of Enugu metropolis and Enugu S...