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A simulation-based decision support system for finite population maintenance logisticsGallion, Mark Steven January 1986 (has links)
This thesis presents a decision support system, MAINTAIN, that was developed to assist maintenance and logistics planners in the evaluation of alternative strategies that might be used in the maintenance of a finite population of end items. The modeled population must consist of a finite number of identical end items, each at age zero at the beginning of the analysis. End items are modeled at their component level, with the lifetime of each component described by a probability distribution. These components are assumed to fail independently of each other and to cause end item failure if any one component should fail. Several component-level preventive maintenance policies are integrated into the modeling system and include age-based replacement, opportunistic lookahead replacement, or no replacement until failure.
Also incorporated into the model is the use of two repair facilities, which function as constraints on the resources available to perform maintenance tasks. One repair facility is used under normal conditions, while the second can be used when the first facility is operating beyond its capacity.
MAINTAIN is a simulation-based modeling system, in that a proposed or actual maintenance system is captured as an input data set and its operation is simulated over the specified planning horizon. Time-series output statistics are produced by the model to allow the analysis of time dependent parameters such as population availability, maintenance costs, spares requirements and repair facility utilization. Output data are available in several forms for use in external analyses. / M.S.
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Is the Share of Agricultural Maintenance Research Rising? Implications for Future Productivity Growth in U.S. AgricultureSparger, John Adam 08 April 2009 (has links)
Agricultural research is susceptible to research deterioration due to biological, climatic, and economic forces. Research deteriorates as the base conditions it addresses change which leaves the resulting information or technology less effective, efficient, productive, and/or relevant. Maintenance research targets deterioration in an attempt to prevent any loss of previous gains. Maintenance research is in contrast to productivity enhancing research which attempts to increase efficiency or productivity beyond previously attained thresholds.
In 1986, Adusei and Norton conducted a survey of agricultural scientists across the United States to measure the amount of commodity based agricultural research devoted to maintenance research (1990). They discovered roughly 35% of all agricultural research related to commodities was spent on maintenance research. A follow-up survey was conducted in 2008 to see if the proportion of maintenance research engaged in agricultural research had risen. In this survey, the amount of maintenance research in non-commodity based agricultural research was also measured. The percentage of agricultural commodity research engaged in maintenance research was found to have risen to roughly 41%. In contrast, the percentage of maintenance research in agricultural non-commodity research was found to be roughly 29%.
An empirical model was developed to explain maintenance research expenditures. Agricultural research funding, climatic conditions, land degradation, pest and pathogen control, and agricultural production were thought to influence maintenance research expenditures. From these five categories, seven representative variables were included in the model. The model found each category except land degradation to have a statistically significant impact on maintenance research expenditures. / Master of Science
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An investigation into the impact of fairtrade in South AfricaJari, Bridget January 2012 (has links)
World international trade is moving towards more free trade, through globalization and trade liberalization. These moves are guided by trade theories which state that on an aggregated level, nations involved in free trade should benefit, and further that free trade is fair. However, in practice, contradictory views have been raised, stating that free trade may not necessarily be benefiting all participants equally. Rather, other nations, especially developing nations, have become worse-off after opening up their markets for free trade. On the other hand, many developed nations have benefited substantially from free trade. Among other factors, the difference in benefits is believed to have been influenced by the types of commodities being traded (where developing nations mainly trade in primary goods and developed nations in anufactured goods) and unequal power relations (some nations for example, the EU and the US, still adopt protectionism in their agricultural sector). In order to address market imbalances resulting from free trade, Fairtrade has arisen. Fairtrade aims to improve international trading conditions in order to benefit small-scale farmers and farm workers in the developing nations. The Fairtrade organization further claims that its principles are in line with sustainable development. However, Fairtrade suffers a credibility gap because there is a lack of independent research to support their claims. To date in South Africa, there is little research examining the claims of the Fairtrade organization. In order to contribute to the Fairtrade discussion in South Africa, this study has investigated the validity of Fairtrade‘s claims that it contributes towards sustainable development. The study utilised primary data, which was collected from ten commercial farms and two small-scale farmer cooperatives located in the Eastern Cape and Western Cape provinces that are/were Fairtrade certified. The main reason for including commercial farmers and small-scale farmer cooperatives in the study was for comparing relative impacts in the two Fairtrade structures. The data was then analysed using a sustainable livelihoods framework, which was developed in the study. The study focussed on investigating the impact of Fairtrade tools, which are minimum prices, premiums, pre-financing and support for long-term relationships, on its intended beneficiaries. Minimum prices offered to producers cover production costs and are above market prices, and Fairtrade premiums are to be invested in developmental projects. Therefore, examining the influence of Fairtrade tools on individuals and communities provides an overview of how Fairtrade influences development. The results of the study show that sampled Fairtrade beneficiaries in South Africa have witnessed substantial positive changes as a result of Fairtrade. The Fairtrade initiative has managed to empower small-scale producers and farm workers, as well as leverage development opportunities for their wider communities. It has supported organizational development in the supply chain, facilitated investment in community development projects and in business-related training. Producers, both commercial and small-scale producers, managed to access a market that offers stable prices, and have gained from minimum prices. Furthermore, small-scale farmers have been allowed an opportunity to expand their business into export markets, and enjoyed an increase in incomes. Fairtrade benefits further trickle down to non-Fairtrade community members, in the form of employment creation and community development. Despite positive effects, Fairtrade producers faced challenges, including high Fairtrade administration costs and a small market for Fairtrade commodities. The study concludes that in the face of challenges, Fairtrade brings economic, social and environmental benefits, but as compared to economic and social development, the impact on environmental development is rather limited. Even though that is the case, Fairtrade offers valuable development opportunities to producers in South Africa.
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