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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 201 to 203 of 203 (0.051 seconds)Spelling suggestions: "subject:"bidirectional"" "subject:"nidirectional""
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PV Based Converter with Integrated Battery Charger for DC Micro-Grid ApplicationsSalve, Rima January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents a converter topology for photovoltaic panels. This topology minimizes the number of switching devices used, thereby reducing power losses that arise from high frequency switching operations. The control strategy is implemented using a simple micro-controller that implements the proportional plus integral control. All the control loops are closed feedback loops hence minimizing error instantaneously and adjusting efficiently to system variations. The energy management between three components, namely, the photovoltaic panel, a battery and a DC link for a microgrid, is shown distributed over three modes. These modes are dependent on the irradiance from the sunlight. All three modes are simulated. The maximum power point tracking of the system plays a crucial role in this configuration, as it is one of the main challenges tackled by the control system. Various methods of MPPT are discussed, and the Perturb and Observe method is employed and is described in detail. Experimental results are shown for the maximum power point tracking of this system with a scaled down version of the panel's actual capability.
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| 202 |
Understanding resilience and coping in child-headed households in Mutasa District, ZimbabweKapesa, Mary Joyce 09 1900 (has links)
Text in English / Zimbabwe had 50 000 child-headed households (CHH) in 2002 and by 2010, the figure had gone up to more than 100 000, making Zimbabwe the African country with the highest number of CHH (UNICEF & UNAIDS 2010). These statistics gave rise to the sprouting of many organisations and programmes aimed at catering for the needs of the affected children. Not much attention is given to what the CHH can do for themselves and how they have be surviving without outside help. The present study explored the resilience factors and coping strategies used by children living in CHH in the Mutasa District, Zimbabwe. The mixed method concurrent triangulation design was used in the study and a constructionist theoretical framework was adopted. Semi-structured interviews and focus group discussions were used to collect data from 28 children in CHH, 46 community members, 24 teachers, 25 child service professionals, 10 advisory panel members, 3 government officials involved in policy formulation and implementation and 5 members of the CHH’s extended family. The Resilience Scale was administered to the CHH and the Tree of Life and problem solving activities were carried out with the children. Resilience scores obtained from the children in CHH were in the high to very high category of resilience. The qualitative data was thematically analysed. The research findings indicate that children in CHH use problem focused coping strategies. Their resilience is anchored in both individual and environmental factors. A Bidirectional Model of Resilience that is based on the findings emerged from the study.Three pathways to resilience that are embedded in this model were identified, furthermore the Self-Efficacy Strengths-Focused Model of Coping was proposed. Intervention strategies to foster resilience in CHH should focus on creating coping enabling environments and strengthening individual characteristics. / Psychology / Ph.D. (Psychology)
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| 203 |
Understanding resilience and coping in child-headed households in Mutasa District, ZimbabweKapesa, Mary Joyce 09 1900 (has links)
Zimbabwe had 50 000 child-headed households (CHH) in 2002 and by 2010, the figure had gone up to more than 100 000, making Zimbabwe the African country with the highest number of CHH (UNICEF & UNAIDS 2010). These statistics gave rise to the sprouting of many organisations and programmes aimed at catering for the needs of the affected children. Not much attention is given to what the CHH can do for themselves and how they have be surviving without outside help. The present study explored the resilience factors and coping strategies used by children living in CHH in the Mutasa District, Zimbabwe. The mixed method concurrent triangulation design was used in the study and a constructionist theoretical framework was adopted. Semi-structured interviews and focus group discussions were used to collect data from 28 children in CHH, 46 community members, 24 teachers, 25 child service professionals, 10 advisory panel members, 3 government officials involved in policy formulation and implementation and 5 members of the CHH’s extended family. The Resilience Scale was administered to the CHH and the Tree of Life and problem solving activities were carried out with the children. Resilience scores obtained from the children in CHH were in the high to very high category of resilience. The qualitative data was thematically analysed. The research findings indicate that children in CHH use problem focused coping strategies. Their resilience is anchored in both individual and environmental factors. A Bidirectional Model of Resilience that is based on the findings emerged from the study.Three pathways to resilience that are embedded in this model were identified, furthermore the Self-Efficacy Strengths-Focused Model of Coping was proposed. Intervention strategies to foster resilience in CHH should focus on creating coping enabling environments and strengthening individual characteristics. / Psychology / Ph.D. (Psychology)
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