Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 396-419). Also available on the Internet.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

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It is expected that South Africa will have to construct as much generating capacity in the next five years as has been constructed over the past 50 years. Industrialization and urbanization dictates that the larger portion of this increase will be required in the supply areas under the control of Municipal Electricity Undertakings, which means that these undertakings will have to anticipate rapid growth in their infrastructures. This will put a tremendous strain on their resources of revenue, materials and labour, and it is obvious that comprehensive and co-ordinated policies are required to be developed to enable these undertakings to deliver the electrical energy to the final consumers at the lowest possible cost. The Electricity Undertaking is a business organization with unusually difficult managerial problems in all its functional areas. Its personnel are adversely affected by the vast area of supply and by the resulting difficulty of direct supervision and control. The capital cost of electrical equipment is high, and there may be a tendency to reduce the initial cost by ignoring the long term costs associated with the selection of equipment. Electricity pricing is very difficult, as electricity is not a uniform product. The consumption patterns of the consumers causes severe peaking of loads to occur, resulting in very low utilization )f the capital equipment involved, and which can threaten to overload existing networks. These problems are compounded by the fact that the undertaking is a monopoly and as such is not driven by the free-market motivating forces, such as a profit motive and the constant need to improve to meet competition. There is thus no motive to seek optimum solutions to the many problems. It is shown that the Load Factor is an indication of the efficient use of scarce resources, and that it is similar to measurements of profitability, such as Return-on-Investment, etc. It is therefore possible to replace the missing drive for profit and product improvement by the need to constantly improve the load factor. By making this the main objective of the undertaking many of the stated problems are put in their correct perspective. Maintenance becomes important, as power failures adversely affect the load factor. More care is exercised in equipment selection, as long term energy losses are taken into account. Electricity pricing and its effect on consumer consumption patterns becomes important. The concerted effort to improve the load factor is referred to as load management. Due to the tremendous increase in electricity consumption which is expected over the next decade it is certain that load management will play an ever increasing role. Load Management is defined as the sustained attempt at modifying the load curve. Soft load management refers to pricing policies and incentive schemes designed to induce users to shift their loads .out of the peak periods. Hard load management physically switches customer loads. This thesis examines the results obtainable from various methods of load management including off-peak incentive tariffs, on-peak-reduction rebates, the use of current limiters, peak load reduction by means of voltage reduction and remote control of water heater cylinders. It is shown that whereas Sasolburg saves around R7S0 000.00 p.a. and Randburg saves over Rl,5-million p.a.,other towns such as Pretoria and Pietermaritzburg find their geyser control systems ineffective, and are phasing them out. It has hitherto not been possible to determine the actual savings which would result from the installation of a geyser control system, or to determine the optimum number of controlled geysers. The result was that some undertakings would install a control system at considerable expense which resulted in minimal savings, while other towns forego the opportunity to save hundreds of thousands of rands in reduced demand charges. In this thesis, the author develops a feasibility study model which permits the system load curve to be analysed and the viability of a geyser control system to be determined. The model was tested against the controlled and uncontrolled load curves of Somerset West, and was found to be accurate. It was shown that a geyser control scheme is a very viable proposition for those undertakings where the feasibility study shows a contribution of more than 0,5 KVA per geyser towards peak load reduction. This forms the basic guideline for the selection of an appropriate form of load mangement, and guidelines are presented to develop supporting policies in all fields of the undertakings' functions. In order to facilitate correct decision-making and to assist in the development of comprehensive policies, a database of concepts and models is presented in the various fields and various misconceptions are dicussed. The guidelines have been applied by several electricity undertakings. By using the Feasibility Study Model it was shown that the proposed installation of 4000 geyser control units at Oudtshoorn, at a cost of over RI-million, was not viable. The Feasibility Study Model permits the savings to be calculated for different numbers of geysers and it was shown that the system saturates at about 1500 controlled geysers. By reduci ng the number of controlled geysers to around 1500 the installation cost will be reduced by about R500 000.00 and the system will show a net operating savings , " of RI05 540.00 in the first year, increasing as ESCOM increases its tariffs. The application of these principles conceivably prevented the needless expenditure of RI-million on a system that would have run at an operating loss of over R17 000.00 p.a. The feasibility study model was applied to the Stanger load curve to determine the correct selection of load management. The results indicate excellent response to geyser control, and showed that a system controlling 2500 geysers, costing R498 500.00 would show a gross savings of R297 000.00 in the first year, rising to RSI0 000.00 within 5 years if ESCOM increases its tariff by 10% p.a. Based on these results and recommendations the Department of Finance gave ad hoc approval to the Borough of Stanger for the additional expenditure in the current financial year to install the control equipment. The guidelines indicated a similar result for Tongaat, where the gross savings would be R360 000.00 in the first year, increasing to R637 680.00 within 5 years if ESCOM increases its tariff by 10% p.a. The estimated cost of the control equipment is R493 649.00. In complete contrast, the feasibility studies for geyser control undertaken on the Ballito load curve showed a contribution of less than 0,5 KVA per geyser, which indicated that the alternative forms of load management should be implemented. The results are contained in the case studies. / Thesis (DBA)-University of Durban-Westville, 1986.

This dissertation is undertaken under the auspices of both the CSIR, Division of Mining Technology and the University of Natal, School of Mechanical Engineering. The CSIR have outlined two fundamental objectives of the dissertation. Firstly, the need for competent design engineers has become increasingly evident. To this end, an evaluation and research into the science of design methodology has been conducted and regarded as a significant component of the thesis. The rationale behind this aim is that the subject of design has been practiced for thousands of years, but an understanding of the process is comparably in its infancy. The importance of the steps involved in the mechanical design process can in no uncertain terms be overemphasized as the adherence there to results in designs that are least likely prone to failure as well as the attainment of highly efficient product design time scales. This is vitally important more especially when the drive towards multifunctional multidisciplinary teams is rapidly developing in the global market place. Secondly, the CSIR, having done the appropriate market research, have defined the need for the design of a timber handling system to be implemented in a deep level mining environment. It is the authors expressed intent not to separate the theory from the design at hand but rather to allow this thesis to become, for the reader, forum where a holistic and integrated approach to design can be presented. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

In order to facilitate the materials handling requirements of production structures configured for Mass Customisation Manufacturing, the design of requisite materials handling and routing systems must encompass new conceptual properties. Materials handling and routing systems with the capacity to support higher-level management systems would allow for mediated task allocation and structured vertical integration of these systems into existing manufacturing execution and management systems. Thus, a global objective in designing a materials handling and routing system, for such production configurations. is to provide a flexible system mechanism with minimal policy on system usage. With the recent developments in mobile robot technologies, due to various advancements in embedded system, computational, and communication infrastructures, mobile robot platforms can be developed that are robust and reliable, with operating structures incorporating bounded autonomy. With the addition of materials handling hardware, autonomous agent architectures, structured communication protocols and robotic software systems, these mobile robot platforms can provide viable solution mechanisms in realising real-time flexible materials handling in production environments facilitating Mass Customisation Manufacturing. This dissertation covers the research and development of a materials handling and routing system implementation architecture, for production environments facilitating Mass Customisation Manufacturing. The materials handling and routing task environment in such production structures is characterised in order to provide a well defined problem space for research purposes. A physical instance of a functional subset of the architecture is constructed consisting of a semi-autonomous mobile robot platform equipped with the infrastructure for materials handling and routing task execution. The architecture orientates the mobile robot platform in such a way as to present a collection of functional units, integrated and configured for a range of applications, and prevents viewpoints in the sense of monolithic mobile robots less susceptible to reconfiguration and stochastic utilisation. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008.

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Automation of the industrial transformer core assembly process is highly desirable. A survey undertaken by the author however, revealed that due to the high cost of existing fully automated systems, Australian manufacturers producing low to medium transformer volumes continue to maintain a manual construction approach. The conceptual design of a cost-effective automation system for core assembly from pre-cut lamination stacks was consequently undertaken. The major hurdle for automating the existing manual process was identified as the difficulty in reliably handling and accurately positioning the constituent core laminations, which number in their thousands, during transformer core construction. Technical evaluation of the proposed pick-and-place core assembly system, incorporating two mobile robots bearing a common gripper, is presented herein to address these requirements. A unique robotic gripper, having the capability to selectively pick a given number of steel laminations (typically two or three) concurrently from a stack, has the potential to significantly increase productivity. The only available avenue for picking multiple laminations was deemed to be a gripper based on magnetism. Closed form analytical and finite element models for an electromagnet-stack system were contrived and their force distributions obtained. The theoretical findings were validated by experiment using a specially constructed prototype. Critical parameters for reliably lifting the required number of laminations were identified and a full scale electromagnet, that overcame inherent suction forces present in the stack during picking, was subsequently developed. A mechanical docking arrangement is envisaged that will ensure precise lamination placement. Owing to the grippers unwieldy length however, conventional robots cannot be used for assembling larger cores. Two wheeled mobile robots (WMRs) compliantly coupled to either end of the gripper could be considered although a review of the current literature revealed the absence of a suitable controller. Dynamic modelling for a single WMR was therefore undertaken and later expanded upon for the dual WMR system conceived. Nonlinear adaptive controllers for both WMR systems were developed and subsequently investigated via simulation. Neglecting the systems dynamics resulted in analogous, simplified kinematic control schemes, that were verified experimentally using prototypes. Additional cooperative control laws ensuring the synchronisation of the two robots were also implemented on the prototype system.