Thesis (Ph. D.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 10, 2007) Vita. Includes bibliographical references.

The development of co-operatives has been increasingly seen, both globally and in developing countries, as a key strategy for a high economic growth rate, job creation and poverty alleviation. In trying to address these challenges, the South African government has been promoting co-operatives as an instrument for economic growth and socio-economic integration. Despite the realisation of the important role that cooperatives could play, not enough research has been done on the successes and failures of these organisations in achieving economic growth and socio-economic development in countries. The present study is an attempt to address this research gap. The primary objective of this study was to increase the success of co-operatives in South Africa by investigating the prevailing nature of operations of co-operatives and the determinants of the success of these organisations. More specifically, the study gathered qualitative information about co-operatives, identified which factors influence co-operatives in general and investigated which of these factors are the most important determinants of the success of these organisations in South Africa. A census was conducted of the 110 co-operatives registered in the database of the Leadership Academy (LA) of the NMMU Business School. Only 50 executive members of 26 co-operatives participated in the study (response rate of 23.6 percent). The empirical results revealed that the two most critical success factors for co-op success were the handling of finances and leadership; that language groups viewed coop success differently; and that females provide stronger leadership than males in cooperatives. The results also showed that skills development is an important factor in achieving these critical success factors. These results presented important managerial implications for the success of co-operatives.

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Typescript, etc. / Digitized by Kansas State University Libraries

The performance and reliability of wireless communication links can be improved by employing multiple antennas at both ends, thereby creating multiple-input multiple-output (MIMO) channels. However, once multiple co-channel users are added to the system it can be difficult to provide as many receive antennas as transmit antennas, resulting in a so-called overloaded (rank-deficient) system. Under overloaded conditions, maximum likelihood (ML) detection works well, but its exponential complexity prohibits its use and suboptimal linear detectors perform poorly. In this thesis, new signal processing techniques for multi-user overloaded systems using hybrid automatic repeat request (HARQ) protocols are investigated. The HARQ retransmissions are used to form virtual receive antennas, which can efficiently transform an overloaded system into a critically loaded system (i.e. a system with an equal number of transmit and receive antennas). In the first part of the thesis, a multi-user non-cooperative overloaded system is considered. At first, it is demonstrated that the suboptimal linear minimum mean square error (MMSE) detector leads to significant performance degradation compared to an ML detector for such systems. To overcome this drawback, two multi-user transmission schemes are proposed that work well under overloaded conditions. The proposed schemes allow us to apply linear multi-user detection (MUD) algorithms without requiring additional antennas or hardware chains. Monte-Carlo simulations demonstrate that the proposed schemes can result in significant gains in terms of bit-error-rate (BER) and dropped packet performance. In the second part, the performance of multiple HARQ processes for a two-hop multi-source multi-relay decode-and-forward (DF) relaying network with no direct link are analyzed. Dealing with multiple HARQ processes at each relay, a retransmission scheme is proposed that utilizes virtual antennas to achieve increased receive diversity and improved throughput compared to traditional orthogonal (time division) retransmissions. A novel forwarding strategy at the relay(s) to destination link is proposed with the objective of further improving throughput. Finally, the end-to-end outage probability and throughput efficiency of the proposed retransmission and forwarding schemes are found analytically and confirmed with Monte-Carlo simulations.

M.Com. (Business Economics) / Please refer to full text to view abstract

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Cooperative coevolutionary algorithms (CCEA) are a form of evolutionary algorithm that is applicable when the problem can be decomposed into components. Each component is assigned a subpopulation that evolves a good solution to the subproblem. To compute an individual's fitness, it is combined with collaborators drawn from the other subpopulations to form a complete solution. The individual's fitness is a function of this solution's fitness. The contributors to the comprehensive fitness formula are known as collaborators. The number of collaborators allowed from each subpopulation is called pool size. It has been shown that the outcome of the CCEA can be improved by allowing multiple collaborators from each subpopulation. This results in larger pool sizes, but improved fitness. The improvement in fitness afforded by larger pool sizes is offset by increased calculation costs. This study targeted the pool size parameter of CCEAs by devising dynamic strategies for the assignment of pool size to regulate selection pressure. Subpopulations were rewarded with a larger pool size or penalized with a smaller pool size based on measures of their diversity and/or fitness. Measures for population diversity and fitness used in this study were derived from various works involving evolutionary computation. This study showed that dynamically assigning pool size based on these measures of the diversity and fitness of the subpopulations can yield improved fitness results with significant reduction in calculation costs over statically assigned pool sizes.