9 resultados para 338.954
em SAPIENTIA - Universidade do Algarve - Portugal
Resumo:
In the past few years, a considerable research effort has been devoted to the development of transformer digital models in order to simulate its behaviour under transient and abnormal operating conditions. Although many three-phase transformer models have been presented in the literature, there is a surprisingly lack of studies regarding the incorporation of winding faults. This paper presents a coupled electromagnetic transformer model for the study of winding inter-turn short-circuits. Particular attention will be given to the model parameters determination, for both healthy and faulty operating conditions. Experimental and simulation test results are presented in the paper, demonstrating the adequacy of the model as well as the methodologies for the parameters determination.
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Tese de dout., Gestão, Faculdade de Economia, Universidade do Algarve, 2009
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Dissertação de mest., Gestão e Desenvolvimento em Turismo, Faculdade de Economia, Universidade do Algarve, 2009
Resumo:
The region of the Algarve shows huge differences between the coastline where population in the urban areas grows, and the inland rural areas, in some cases very isolated, which frequently have high ageing indexes. This general scenario, with an elderly population with very different economic and social conditions, frames the ongoing PhD research designed as a cross-sectional study of an intentional sample of elderly persons. The basic theoretical framework departs from the perspective of developmental psychology of life-span and the model of selection, optimisation and compensation for optimal ageing (Baltes & Baltes, 1990; Freund & Baltes, 2002). The present study is a first step in the analysis of empirical data collected in the PhD sample (N=156; age range 65 to 97 years; M = 80.4 years; SD = 7.2 years). Its purpose is to assess the cognitive functioning of participants, screening for cognitive impairment and examine the relations between the cognitive status of the subjects and a number of selected variables including educational level, age, physical activity and living contexts of the subjects. We accessed the cognitive status of the participants with the Portuguese version of Mini Mental State Examination (MMSE) finding a 10.3% prevalence of positive cases with cognitive impairment. The results also show significant relationships between the cognitive status accessed by the MMSE and educational level, professional qualification, age, living arrangement and activity level of the participants. The relationship verified between educational level and cognitive status of the participants was the largest correlation found in the study with the variability in educational level accounting for 44.8% of the variability in MMSE score. This results points in the same direction of several lines of research that corroborate the strong intercorrelation between education and cognitive functioning in old age.
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Dissertação de mest., Gestão e Desenvolvimento de Destinos Turísticos, Faculdade de Economia, Univ. do Algarve, 2010
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Dissertação de mest., Marketing, Faculdade de Economia, Univ. do Algarve, 2010
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Dissertação de mest., Ciências Económicas e Empresariais, Faculdade de Economia, Univ. do Algarve, 2002
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Dissertação de mestrado, Tecnologia de Alimentos, Instituto Superior de Engenharia, Universidade do Algarve, 2013
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Dissertação de Mestrado, Aquacultura e Pescas, Especialização em Aquacultura, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015