Demand for high-resolution imaging capabilities for both space-based and ground-based imaging systems has created significant interest in improving the design of multi-aperture interferometry imaging systems. Interferometers are a desirable alternative to single aperture imaging systems due to the fact that the angular resolution of a single aperture system is dependent on the diameter of the aperture and the resolution of the image recording device (CCD or otherwise) which quickly results in increased size, weight, and cost. Interferometers can achieve higher angular resolutions with lower resolution recording mediums and smaller apertures by increasing the distance between the apertures. While these systems grow in both size, mechanical, and computational complexity, methods of testing large scale designs with small scale demonstration systems currently do not exist. This paper documents the performance of a small scale multi-aperture intensity correlation interferometer which is used to view a double slit image. The interferometer consists of 2 avalanche photo-diodes connected to a data acquisition computer. The image is produced by shining light through the double slit image an image containment system. The sensors are placed at the far end of the image containment system, and their voltages are recorded and digitally filtered. This study presents the formulation of the design parameters for the interferometer, the assembly and design of the interferometer, and then analyzes the results of the imaging experiment and the methods used to attempt to prevent unwanted noise from corrupting the expected interference pattern. Codes in C and C++ are used to collect and analyze the data, respectively, while Matlab® was used to produce plots of binary data. The results of the analysis are then used to show that a small scale intensity correlation interferometer is indeed feasible and has promising performance.

The main research problem is the low productivity of small scale maize farmers largely as a result of low adoption rates of recommended practices that could enhance yield levels and improve their incomes and livelihoods, and the inability of extension workers to effectively influence farmers’ decision making process by their lack of appropriate predictive extension planning tools. The problem faced by extension workers is the lack of understanding of the wants and needs of farmers, their preferences and behavioral inclinations towards agricultural innovations. In order to contribute to the understanding of farmers’ behavior change, the study sought to compare the relative influence of personal and social characteristics of farmers with intervening variables as conceptualized by Düvel and Ajzen’s subjective norms, with the objective of determining their predictive potential of farmers behaviors for extension program planning purposes. A secondary objective was to search for additional variables to explain farmer’s adoption behavior by exploring the predictive value of the subjective norm concept The study was carried out in the Leribe and Maluti-a-Phofung districts of Lesotho and South Africa respectively. A structured questionnaire with a Sotho translation was used to collect data from 107 farmers randomly selected from the districts and administered by trained extension staff. The data collected was analyzed using the social sciences (SPSS). In determining the relationships between the independent and dependent variables, Chi-square test of independence, correlation and regressions analysis were used. In all 10 independent and nine intervening variables were selected for the study. The independent variables were location of the farm, membership of farmers association, gender, age, level of education, experience in farming, off-farm income, amount of time spent farming, total farm size and area under maize cultivation. The intervening variables were efficiency perception, need compatibility, need tension, awareness and prominence constituted cognitive aspects derived from Düvel’s Model and the social dimensions adapted from Ajzen’s subjective norm concept were, important people, extension agents, close friends and membership of farmers association. The results suggest that farm size and area under maize cultivation were the only variables that showed any consistent influence with adoption of recommended maize agronomic practices namely: use of improved seeds, lime and fertilizer applications. The association between the remaining variables seems to be more dependent on the type of recommended practice. For example location was found to be significantly associated with the adoption of fertilizer and top-dressing practices but not with lime and the use of improved seed. All the remaining independent variables gender, age, educational level, experience and time spent on the farm appear not to have any significant influence on the adoption of the recommended practices at five percent level of probability. Compared to the independent variables, five out of the nine intervening variables, namely: prominence, awareness, need compatibility, efficiency perception and need tension were consistently found to be highly significantly associated with the adoption of all the four recommended maize agronomic practices at 5% level of probability. On the other hand, the subjective norm variables did not show any consistent association with adoption behaviors of respondents In general the analysis suggest a lower than expected contribution to variation as the results contradicts the hypothesis that farm and farmer characteristics influence adoption behavior. This is supported by the fact that, except for top- dressing where the characteristics of the farmer and farm contribute about 40% to the explanation to total variation, the rest all fall below 20 %. In contrast, the evidence shows that the intervening variables – those with cognitive dimensions, showed a high degree in explaining variation in the adoption behavior in all the production practices studied. The power of explanation ranged from 49% in the case of adoption of improved seed practices to 77.7% for the use of lime. The results provide strong evidence in support of the contention that, the intervening variables of cognitive in nature, are the likely precursors of decision making through which the influence of independent variables become manifested in behavior. The results also show that need, perception and knowledge related variables mediate between intentions, personal variables and the environment and decisions on adoption. This study confirms and opens the way for the search for more intervening variables with the potential to extend the epistemology of extension science. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Agricultural Economics, Extension and Rural Development / unrestricted

The near collapse of extension services in Limpopo Department of Agriculture (LDA) particularly evident in its failure to respond to the needs of the majority of small-scale farmers, presents a major problem from an agricultural and rural development point of view. This calls for an urgent and holistic intervention, in terms of an appropriate extension approach and policy, and prompted this research focusing on the search and development of an appropriate extension approach and corresponding policy for the LDA. For such a policy to be acceptable at the operational level, the emphasis has been on maximum involvement and participation of extension personnel. A total of 324 front line extension workers and managers, representing a 40 percent sample, were involved in group interviews in which their opinions were captured in semi structured questionnaires after exposure to nominal group and Delphi techniques. From the research no particular extension model emerged, but rather a series of principles, which, depending on a specific situation, could be combined and implemented to different degrees. Respondents’ opinions regarding these principles and their dimensions formed the basis of recommendations for a policy framework. These recommendations, based on informed opinions of respondents, include a need-based but priority focused approach relying on a compromise between felt and unfelt needs rather than only the felt needs of community members. For the implementation of participatory development that will ultimately allow for community empowerment and ownership, institutional linkage structures are recommended that provide for effective coordination and integrated operational activities, and having primarily a commodity focus. A strong knowledge support system, having as target audience front-line extension workers rather than farmers, is important in view of the large percentage of under-qualified extension staff. A national (or provincial) monitoring and evaluation programme is seen as an issue of high priority, with a stronger emphasis on monitoring using behaviour determinants (forces of change) as main criteria, but covering also the full range of in- and output criteria in the evaluation process, which if used together with a purposeful and programmed approach, can go a long way in improving current and future extension in Limpopo. / Thesis (PhD)--University of Pretoria, 2009. / Agricultural Economics, Extension and Rural Development / unrestricted

Thesis (M.Sc. Agriculture (Agricultural Economics)) -- University of Limpopo, 2021 / Groundnut is one of the most important agricultural crops in South Africa. It provides economic and health benefits to the society. Its production, processing and marketing provides employment to several individuals in South Africa. The objectives of the study were: to identify and describe the socio-economic characteristics of small-scale groundnut farmers, analyse the determinants of commercialization and the factors influencing the choice of market outlet in Capricorn district. The study was conducted in three villages (Ga-Maja, Ga-Mphahlele and Moletjie). Purposive sampling technique was used to select 110 small-scale groundnut farmers. Semi-structured questionnaires were used to collect data from the small-scale groundnut farmers through face-to-face interviews. The data was analysed using the descriptive statistic, Logistic Regression and Multinomial Logit model. SPSS and STATA software were used to process the data. The results indicated that quantity of groundnut produced, occupation, marital status, household size, land size, vehicle ownership, access to credit and extension contact significantly influenced the commercialization and the choice of market outlet of the small-scale groundnut farmers in the study area. The study recommends that the government in collaboration with universities and agricultural colleges as well as the private sector initiate an extension programme that will focus on small-scale farmers, rather than on emerging and commercial farmers only. This will enable the small-scale famers to get access to information on the market, production, price and other agricultural related activities. It further recommends that the Department of Agriculture visit areas where farmers produce the same type of crops and offer them incentives to pool their resources and market their produce collectively. This will improve the bargaining position of the small-scale farmers as well as the means of lowering transaction costs. / National Research Foundation (NRF)

World food security will be one of the greatest global challenges in the 21st century and utilisation of an increased range of food crops is generally regarded as being vital to meeting this challenge, including the use of legumes. Bambara groundnut (Vigna subterranea) is an African indigenous legume that shows great potential to improve the food and economic security of small scale farmers living in semi-arid regions of South Africa. This study sought to investigate the potential for Bambara groundnut to enhance the food and economic security of small scale farmers in the Capricorn District of Limpopo Province, South Africa. A total of 43 Bambara groundnut producers were interviewed about Bambara groundnut production and their perceived enablers and barriers of utilizing Bambara groundnut. The study found that the majority of Bambara groundnut producers were old (>65 years of age), female small scale farmers who produced the crop for primarily household use. There were however a small number of farmers who produced Bambara groundnut on a larger scale, mostly to sell. Most farmers perceived that local demand was higher than supply and were able to obtain a high market value for Bambara groundnut. There appeared to be potential economic opportunities for many of the farmers to sell Bambara groundnut. The main reason why most farmers in this study did not sell Bambara groundnut was because the yields they obtained were too low. The main enablers perceived by farmers for Bambara groundnut production were a) The high nutritional value of Bambara groundnut; b) The good taste of the seeds; c) The nitrogen fixation properties of this legume and its ability to improve soil fertility; d) The legume intercrops well with maize; e) Bambara groundnuts high drought resistance; f) Cultural traditions associated with Bambara groundnut; and g) Use as animal feed. The main barriers were a) Low yielding characteristics of Bambara groundnut; b) Lack of available farmland; c) Lack of irrigation; d) Poor land management practices; e) Low soil fertility; and f) The crop's susceptibility to water logging. Overall the farmers were positive about Bambara groundnut production and could potentially benefit from advancements made in this sector of agriculture. The study concludes with recommendations to help improve small scale farmers' production of Bambara groundnut with the aim of improving their food and economic security.

As wind turbines are increasingly being adopted for meeting growing energy needs, their implementation for personal home use in the near future is imminent. There are very few studies conducted on small-scale turbines in the one to two meter diameter range because the power generated at this scale is currently not sufficient to justify the cost of installation and maintenance. The problem is further complicated by the fact that these turbines are normally mounted at low altitudes and thus there is necessity to have the optimum operating regime in the wind speed range of 3-10 mph (1.34 -- 4.47 m/s). This thesis discusses two methods for increasing the efficiency of horizontal axis small-scale wind energy conversion systems, 1) adding a diffuser to increase the wind speed at the rotor and 2) designing tubercles to enhance the flow characteristics over blades. Further, it was identified during the course of thesis that for simple installation and maintenance in the residential areas vertical axis turbines are advantageous. Thus, the second chapter of this thesis addresses the design of vertical axis turbines with power generation capability suitable for that of a typical US household. The study of the diffuser augmented wind turbine provides optimum dimensions for achieving high power density that can address the challenges associated with small scale wind energy systems; these challenges are to achieve a lower start-up speed and low wind speed operation. The diffuser design was modeled using commercial computational fluid dynamics code. Two-dimensional modeling using actuator disk theory was used to optimize the diffuser design. A statistical study was then conducted to reduce the computational time by selecting a descriptive set of models to simulate and characterize relevant parameters' effects instead of checking all the possible combinations of input parameters. Individual dimensions were incorporated into JMP® software and randomized to design the experiment. The results of the JMP® analysis are discussed in this paper. Consistent with the literature, a long outlet section with length one to three times the diameter coupled with a sharp angled inlet was found to provide the highest amplification for a wind turbine diffuser. The second study consisted of analyzing the capabilities of a small-scale vertical axis wind turbine. The turbine consisted of six blades of extruded aluminum NACA 0018 airfoils of 0.08732 m (3.44 in) in chord length. Small-scale wind turbines often operate at Reynolds numbers less than 200,000, and issues in modeling their flow characteristics are discussed throughout this thesis. After finding an appropriate modeling technique, it was found that the vertical axis wind turbine requires more accurate turbulence models to appropriately discover its performance capabilities. The use of tubercles on aerodynamic blades has been found to delay stall angle and increase the aerodynamic efficiency. Models of 440 mm (17.33 in) blades with and without tubercles were fabricated in Virginia Tech's Center for Energy Harvesting Materials and Systems (CEHMS) laboratory. Comparative analysis using three dimensional models of the blades with and without the tubercles will be required to determine whether the tubercle technology does, in fact, delays the stall. Further computational and experimental testing is necessary, but preliminary results indicate a 2% increase in power coefficient when tubercles are present on the blades. / Master of Science

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The world is increasingly being faced with the challenge of effectively exploiting available renewable energy resources, not only to meet an ever growing energy demand, but also to preserve the available amount of fossil fuels and to reduce the amount of carbon dioxide emissions released into the atmosphere by fossil fuelled power stations. Hence, every available renewable energy resource, even small rivers has a contribution to make in the attempt to reduce the amount of fossil fuel generated electricity. The focus of this study is the design and installation of a low cost grid-connected 10 kW micro hydro power system (MHPS). The process to determine the potential of the available water resource is first to be presented. The environmental aspects of these systems, based on the study that is undertaken for the implementation of the landmark example, are discussed. The complete design of a micro hydro power system for a specific site is presented. This design is based on using commercially available components and equipment in an attempt to minimise the total cost of a micro hydro power system. The designed micro hydro power system is installed in-field and the predicted performance of the designed system is verified with measured results of the implemented system. Based on the results of the micro hydro power system landmark example, it is shown through a complete economic study, that this investment is very worthwhile. / AFRIKAANSE OPSOMMING: Die wêreld word daagliks meer en meer uitgedaag om beskikbare alternatiewe energiebronne effektief te benut, nie net om in die groeiende elektrisiteits aanvraag te voorsien nie, maar ook om die beskikbare fossiel brandstowwe te beskerm en ook om die hoeveelheid koolstofdioksied gasse wat deur fossiel brandstof kragstasies vrygestel word, te verminder. Dus het elke beskikbare alternatiewe energiebron, selfs klein riviertjies, ‘n bydrae om te lewer tot die poging om die hoeveelheid elektrisiteit wat deur fossiel brandstowwe opgewek word, te verminder. Die fokus van hierdie studie is op die ontwerp en implementering van ‘n lae koste netwerk gekoppelde 10 kW mikro hidro kragstelsel. Eerstens word die proses om die potensiaal van die beskikbare waterbron te bepaal, bespreek. Al die omgewings aspekte van hierdie mikro hidro kragstelsels word dan bespreek. Dit is ten volle gebaseer op die studies wat gedoen is vir die implementering van hierdie landmerk voorbeeld. Die volledige ontwerp van ‘n mikro hidro kragstelsel, vir ‘n spesifieke terrein, word bespreek. Hierdie ontwerp is hoofsaaklik gebasseer op die gebruik van kommersieel beskikbare komponente met die doel om die totale koste van die stelsel te minimeer. Die stelsel wat ontwerp is, is geïnstalleer op die terrein en die verwagte prestasie van die stelsel is toe geverifieer met gemete resultate van die geïnstalleerde stelsel. ‘n Volledige ekonomiese studie wat gebaseer is op die resultate van die geïnstalleerde stelsel, word dan bespreek en daar is gevind dat hierdie stelsel werklik finansieel die moeite werd is. / Centre for Renewable and Sustainable Energy Studies

The sustainability of grouper culture as an alternative livelihood option for coastal fishers was investigated in the southern provinces of Thailand. A sequenced approach using qualitative and quantitative research methods was used to explore factors that could undermine the potential for grouper culture to contribute to a sustainable livelihood. A study was initially conducted in 28 villages in 6 provinces in southern Thailand to provide baseline information on grouper aquaculture and fisheries, focusing on culture practice, the actors and institutions involved in grouper culture and beneficiaries. Factors contributing to the variation in levels of uptake of grouper culture between provinces was explored. This initial overview facilitated the description of the grouper culture system in terms of its boundaries, hierarchies, interconnections and processes and the development of a framework for the assessment of the sustainability of the grouper culture system. A case study approach was used to investigate in-depth the role and sustainability of grouper culture at the community and household level. Three communities were selected for study in Trang and Satun provinces. Research was guided by the sustainability assessment framework, which comprised five components: Livelihoods, Institutions, Environment, Markets and Production Systems. Data was collected using qualitative, participatory methods and a quantitative survey. The research found that grouper culture has the potential to contribute to a sustainable livelihood for coastal fishers in southern Thailand, although problems with fish disease and mortality, fluctuations in the availability of seed fish and water quality undermine the ability of most farmers to obtain the maximum benefit from grouper culture. Non-technical factors including motivation and incentive, access to financial capital and levels of social capital were also observed to influence sustainability of grouper culture. Grouper culture was found to be an activity in which members of all wealth groups could participate with institutional support, access to credit, and access to wild sources of seed and feed. It is unlikely to provide a suitable alternative to fishing, as the two activities contribute in different ways to the livelihoods of coastal households, but may support livelihood diversification.

The intergenerational continuity of knowledge has become a concern as small-scale societies worldwide balance the challenges of adapting to environmental change associated with globalization while retaining continuity in their ways of life. This dissertation examines the intergenerational continuity of environmental knowledge through the conceptual lens of an Ethnoecology of Practice framework (EofP) developed to guide this research. Integrating insights from political ecology, social wellbeing and adaptive learning, the EofP provides theoretical and methodological tools based on practice theory to examine the knowledge of small-scale societies. Based on fieldwork in the community of Ponta Negra (Atlantic Forest Coast, Brazil), this dissertation uses a qualitative case study strategy of inquiry guided by a phenomenological worldview. Methods included participant observation, semi-structured interviews covering livelihoods, life histories and marine and terrestrial knowledge themes, document review and a census. Chapters 4 and 5 examine the perception of marine and terrestrial natural resources by tracing their social life from harvesting grounds to exchange and consumption sites. Chapters 6 and 9 analyse historical and contemporary adaptation to environmental change. While Chapter 6 describes the adoption of the pound net fishery, Chapter 9 illustrates contemporary modes of learning associated with natural resource harvesting and presents the processes associated with production of new knowledge through the example of local participation in the tourism economy. Chapter 7 examines local perspectives on livelihood transition from a social wellbeing perspective and highlights factors underlying the continuity of natural resource harvesting practice in Ponta Negra. Chapter 8 discusses how the term Caiçara, as used in biodiversity conservation and tourism development discourses, circumscribes the relation between coastal people and their local environments to a subsistence economy, denying their current economic engagements as well as their desires and aspirations. This dissertation contributes to ethnobiological understandings of the intergenerational continuity of knowledge by providing a framework and grounding evidence that demonstrates how knowledge is generated through context-specific practice attuned to dynamic environments that leads to individual innovation. It provides a theoretical contribution to our understanding of framing and creating processes inherent to human-in environment relations that lead to fluidity in ways of life over time.

Magister Philosophiae - MPhil / Poverty dynamics and livelihood challenges among small-scale fishing communities on Lake Kariba (Zimbabwe) The aim of this study was to assess poverty among small-scale fishing communities on Lake Kariba (Zimbabwe) as well to as identify livelihood challenges that confront them. Two fishing communities were used as case studies and were uniquely selected from among the many fishing camps/villages dotted along the Zimbabwean shoreline of Lake Kariba. Depending on gear type, fishing activities on Lake Kariba target both the smaller-sized Kapenta species and larger species such as the bream and the tiger. Fishing activities are a major livelihood source for fishers in the two case studies upon which they obtain food and derive income to address other family needs. Mutual linkages and exchanges also exist between fishing camps/villages and communal areas where land-based activities such as cropping and livestock rearing are carried out. Before fieldwork, there was a pre-conceived notion that members of fishing communities on Lake Kariba were very poor. Although the fishers expressed desires for a better life than they were experiencing, they did not consider themselves poor. Instead, they rated their economic position as well off compared to some of their urban counterparts. However, on further interrogation, the study revealed that the fishers were facing a set of vulnerabilities that is commonly associated with the fishing profession. These vulnerabilities had substantial impacts on the livelihood system of these fishers. Using vulnerability ladders, a picture was painted depicting the severity of these vulnerabilities. It emerged that fishers were more vulnerable to existing state institutions that are designed to manage access to and the use of natural resources in the country. There are several reasons to suggest why this is the case which include, (i) the high cost of accessing the fishery, (ii) the stern measures in place that restrict access to and use of the fishery, and (iii) the punitive measures imposed for contravening rules of access and use of the fishery. Although restricting access is in line with the principle of long run sustainability of the fishery, it may threaten the development of the fishing industry and impact negatively on livelihoods of communities involved. Unlike fisheries elsewhere in the world, Lake Kariba is not viewed as a vehicle for reducing poverty and achieving food security. On the contrary, government places emphasis on preserving and enhancing the natural environment both aquatic and non-aquatic with a view to sustaining tourism. Under such a paradigm, fishing is viewed as a threat to the natural environment and requires strict management. Heavy fines are therefore imposed on users that violate the rules of access. Many of the fishers have had their properties attached after failing to raise the necessary amounts to cover the fines. By shifting away from the promotion of fisheries, government has accelerated the decline of the small-scale fishing industry on Lake Kariba, through narrowing the fishers action space and creating an environment conducive for corruption. The decline has subsequently shrunk the livelihoods base of local communities as well as many others who are associated with the fishing industry. While the sustainability of the fishery is paramount, government needs to reconsider its strategy on governing and managing fisheries on Lake Kariba. Given enough support, small-scale fisheries on Lake Kariba have the potential to contribute significantly to the country’s Gross Domestic Product. Small-scale fisheries have also proved their resilience in the wake of the severe economic crisis that Zimbabwe experienced between 2007 and 2009. During this period, there were widespread shortages of basic food items in the country and the demand for fish and fish products rose drastically. The fishers reported that there was an increase in the demand for fish during the crisis period to the extent that they could not supply enough to satisfy the market. This supports the observation by the United Nations (2010) that fisheries, in particular small-scale, can play an important role in the economy in terms of livelihoods, poverty reduction and food security. Fishing activities are also the perfect complement to other land-based livelihood activities for communities that live in close proximity to large water bodies.