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  • About
  • 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.
381

[en] DAILY ELECTRICITY FORECASTING IN LOAD LEVELS, COMBINING STATISTICAL AND COMPUTATIONAL INTELLIGENCE TOOLS / [pt] PREVISÃO DA CARGA DE ENERGIA DIÁRIA EM PATAMARES COMBINANDO TÉCNICAS ESTATÍSTICAS E DE INTELIGÊNCIA COMPUTACIONAL

DOUGLAS ALEXANDER ALVES DE FARIAS 31 March 2009 (has links)
[pt] Esta dissertação apresenta um estudo sobre o comportamento da carga de energia agregada em intervalos temporais dentro de um mesmo dia. Esse tipo de agregação já vem sendo utilizado no setor elétrico brasileiro, sob a forma de três patamares de carga, denominados leve, média e pesada. No entanto, tais patamares são sempre obtidos indiretamente, a partir da agregação da carga horária, não tendo sido encontrado, até a publicação dessa dissertação, nenhum tratamento de forma direta dos mesmos. O trabalho desenvolvido na dissertação descreve matematicamente o cálculo dos três patamares de carga e faz uma análise das séries dessas variáveis, verificando suas características próprias, relações entre si e a influência de variáveis exógenas. Apresenta, também, a modelagem de alguns métodos de previsão para essas séries, empregando técnicas tanto estatísticas quanto de inteligência computacional e propõe um modelo híbrido de previsão, combinando regressão dinâmica, classificador de padrões, lógica nebulosa e um método para combinar os padrões. No modelo proposto, a regressão dinâmica é empregada na previsão da carga diária global, usada para adequar os perfis, descritos de forma normalizada, aos níveis reais das séries. Os perfis são obtidos a partir de um classificador de padrões baseado na técnica subtractive clustering. A combinação dos perfis, que compõem a previsão dos patamares para o horizonte desejado, é feita por um sistema de lógica nebulosa, que usa a temperatura como variável de entrada, tratando de forma intrínseca relações não lineares entre essas variáveis, e um método que trata a saída do sistema nebuloso de forma empírica. / [en] This dissertation presents a study of electricity load aggregated in time intervals into the same day. This type of aggregation has been used by the Brazilian´s electrical sector in the form of three load levels called low, middle and high. However, these load levels were always indirectly achieved from the hourly load aggregation, and it was not found any direct treatment of them as a series up to this publication. The work developed in this dissertation describes mathematically the calculation of the three levels of load and makes an analysis of the series formed by these variables checking their own characteristics, the relationship among themselves and the influence of exogenous variables. It also shows the modeling of some forecast methods for such series employing techniques of both statistics in computational intelligence, introduces the level profile concept and proposes a hybrid model of forecasting, formed by dynamic regression, pattern classification and fuzzy logic, to predict the load level pattern. In the proposed model, the dynamic regression is used in the forecasting of the daily global load that is used to match the resulting pattern, described in a normalized way to the actual load values. The profiles are obtained from a classifier based on the subtractive clustering technique. The combination of the profiles that compose the level pattern forecast to the desired horizon is carried out by a fuzzy logic system that uses the temperature as input variable intrinsically treating non-linear relationships between load level and temperature variables.
382

Bioecologia e manejo do ácaro-vermelho-das-palmeiras, Raoiella indica Hirst (Acari: Tenuipalpidae), no centro-sul do Brasil / Bioecology and management of the red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae) in mid-southern of Brazil

Barroso, Geovanny Soares Pauferro 15 April 2019 (has links)
Raoiella indica é uma severa praga de coqueiro, bananeira e plantas de importância paisagística. Os danos causados nas plantas hospedeiras iniciam-se pelo amarelecimento das folhas basais, seguida por necrose dos tecidos e secamento das folhas. Os objetivos desse trabalho foram: determinar a distribuição de R. indica e ácaros associados no centro-sul do Brasil; determinar os níveis populacionais de R. indica no estado de São Paulo; avaliar a sobrevivência de R. indica na ausência de alimento e diferentes níveis de umidade relativa; avaliar o potencial de ácaros fitoseídeos sobre R. indica; e avaliar o efeito de produtos químicos sobre esta praga. Raoiella indica foi encontrado no Distrito Federal e em 49 municípios de 9 estados, das quais, o mais meridional foi Iporã, estado do Paraná. Dos ácaros Mesostigmata associados a praga, Euseius citrifolius Denmark & Muma foi a espécie mais amplamente distribuída, sendo coletado em quase todos os estados. Os níveis populacionais de R. indica variaram de entre 0,2 a 2,5 ácaros/cm2 (46 a 599 ácaros por folíolo) em Marília e de 0,3 a 1,4 ácaros/cm2 (88,2 a 418 ácaros por folíolo) em Piracicaba. Euseius citrifolius foi o predador mais abundante em Marília, enquanto Amblyseius tamatavensis Blommers foi o predador mais abundante em Piracicaba. O tempo de sobrevivência de R. indica e T. urticae na ausência de alimento em diferentes níveis de umidade foi maior na fase adulta. Umidades abaixo de 47% diminuíram drasticamente o tempo de sobrevivência de todos os estágios. Das espécies de Phytoseiidae, A. tamatavensis mostrou melhor desempenho de predação e oviposição quando alimentados com ovos e ninfas de R. indica, como também se desenvolveu e reproduziu alimentando-se exclusivamente desta praga. Dos produtos testados, o fenpiroximato causou mortalidade de 100% em R. indica. Dos produtos utilizados sobre os predadores, o fenpiroximato foi o mais tóxico para os fitoseídeos, sobretudo em Iphiseiodes zuluagai Denmark & Muma. Os resultados desse estudo sugerem que o estabelecimento de R. indica além do sul do Paraná é possível em microclimas favoráveis ao seu desenvolvimento. Além disso, os estudos indicaram que em São Paulo os altos níveis de precipitação no verão e as baixas temperaturas durante o inverno afetam negativamente os níveis de R. indica. A possibilidade de uso de A. tamatevensis como agente de controle de R. indica precisa ser melhor estudada em condições de campo. / Raoiella indica is a severe pest of coconut, banana trees, and floristic plants. The damage caused to the host plants begins by basal leaves yellowing, followed by tissue necrosis and drying of the leaves. The objectives of this study were: to determine the distribution of R. indica and associated mites in the south-central Brazil; determine population levels of R. indica in São Paulo state; assess the survival of R. indica in the absence of food and different levels of relative humidity; assess the potential of phytoseiids mites on R. indica; and to evaluate the effect of chemicals on the pest. Raoiella indica has been found in the Federal District and in 49 municipalities in 9 States, of which the southernmost was Iporã, Paraná state. Among the mesostigmatid mites associated with this pest, Euseius citrifolius Denmark & Muma was the most widely distributed species occurring in almost all states considered in this study. In Sao Paulo, levels of R. indica varied of between 0.2 to 2.5 dust mites/cm2 (46 to 599 mites per leaflet) in Marília and 0.3 to 1.4 mites/cm2 (88.2 to 418 mites per leaflet) in Piracicaba. Euseius citrifolius was the most abundant predator in Marília. In Piracicaba, Amblyseius tamatavensis Blommers was more abundant. The survival time of R. indica and T. urticae in the absence of food in different levels of moisture was greater in the adult stage. Humidities below 47% decreased drastically the time of survival of all stages. Amblyseius tamatavensis showed better performance of oviposition and predation when fed with eggs and nymphs of R. indica, and developed and reproduced feeding exclusively on this pest. Of the products tested, fenpiroximate caused 100% mortality in R. indica. All products had efficiency above 80%. Fenpiroximate was most toxic for phytoseiids, especially of Iphiseiodes zuluagai Denmark & Muma. The results of this study suggest that the establishment of R. indica beyond southern Paraná is possible in microclimates favorable to its development. In addition, the studies confirm that in São Paulo the high levels of precipitation in summer and low temperatures during winter negatively affect the levels of R. indica. The possibility of using A. tamatavensis as a biological control agent of R. indica requires further evaluation.
383

The Site-specific Influence of Gene-by-diet Interactions on Trabecular Bone in Male Mice

Krittikan Chanpaisaeng (7013240) 13 August 2019 (has links)
<p>Osteoporosis and fractures are debilitating skeletal problems. Accumulating the highest peak bone mass in both cortical and trabecular bone (Tb) as well as developing strong Tb microarchitecture play an integral role in preventing bone loss and osteoporotic fractures later in life. Because Tb is modulated by genetics (G) and environment (e.g. diet, D), my dissertation research focuses on the influence of dietary calcium (Ca) intake, genetics as well as GxD interaction controlling Tb phenotypes in two clinically relevant skeletal sites, i.e. the femur and the L5 vertebra. Male mice from 11 in bred lines and 51 BXD recombinant inbred (RI) lines were fed either adequate (Basal, 0.5%) or low (0.25%) Ca diets from 4-12 weeks of age. We used micro-computed tomography to measure Tb mass and microarchitecture phenotypes. We systematically proved that there are site-specific effects of diet, genetic, and GxD interactions influencing Tb phenotypes. This indicates that there are unique genetic effects modulating Tb at each bone site. Therefore, we conducted a genetic mapping experiment using the 51 BXD RI lines separately for each bone site. We coupled genetic mapping analysis with bioinformatics analysis to identify novel genetic variation and candidate genes accounting for the variation in each phenotypes. The findings from this work serve as a foundation for future research to identify novel pathways and genes underlying the development of Tb as well as an adaptation to Ca insufficiency.</p> <br> <p> </p>
384

What is the role of publishing industry in supporting and promoting isiZulu fiction?

Magudulela, Veronica Winile Mirriam 24 July 2014 (has links)
Thesis (M.A.)--University of the Witwatersrand, Faculty of Humanities, African Literature, 2014. / The purpose of this research project was to investigate the role of the publishing industry in supporting and promoting isiZulu fiction in South Africa. The research first highlighted the contribution made by the missionaries in the 19th century in publishing literature in indigenous languages in general and in isiZulu fiction in particular. This aspect followed by a discussion of the impact of apartheid’s publishing policies on literature in indigenous African languages. This section then followed by the discussion of the strategies and initiatives that have been introduced in order to preserve and promote this literary tradition in the post-apartheid period. This research assessed OUPSA’s book chain process in order to investigate how the book industry contributes to the post-1994 initiatives of promoting creative writing in indigenous languages. It argued that book publishing is not the end of the book provision process, instead marketing and distribution chain, selection of fiction in schools and libraries, lack of experience of librarians, shortage of African languages fiction and financial resources in libraries as well as inconclusiveness of government policies play a huge role in the distribution process of isiZulu fiction which is pivotal to the sustainable existence of a publishing industry. In this research project, different aspects of the book chain process were investigated, such as: publishing and distribution, schools and public libraries, schools and education and literacy level to find out the link between publishing and libraries and schools. It is hoped that the findings of the investigation identified the significant inhibiting factors which may prevent the provision of isiZulu fiction books to libraries and schools that may have been caused by the methods in which books were commissioned, marketing strategies and implementation of the language policy, especially as to how it affects the promotion and rejuvenation of literatures in African languages.
385

The contribution of intelligence, learning strategies, and personal development to engineering students' academic performance

Skuy, Melissa Ann January 2003 (has links)
A research report submitted to the Faculty of Humanities, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Masters of Education (Educational Psychology), 2003 / Previous studies have addressed the question whether intellectual ability (as measured by the Raven's Progressivp Matrices Tests) is related to academic performance in engineering (Rushton & Skuy, 2000; Rushton, Skuy & Fridjhon, 2002; Rushton, Skuy & Fridjhon, 2003). The question arose of whether nonintellective (personality and attitudinal factors) playa larger role at this level, than intelligence, in determining academic performance in engineering university students. Accordingly, data were yielded for 93 percent (N=100) of the second year Chemical Engineering class in terms of their performance on various measures. These included two measures of intellectual ability, namely the Ravens Advanced Progressive Matrices (RAPM) and the Organiser (of The Learning Propensity Assessment Device), together with a measure of learning strategies and attitudes (Learning and Study Strategies Inventory), locus of control (Locus of Control Inventory) and self-esteem (Coopersmith Self-Esteem Inventory). The students' academic results comprised the December 2002 and June 2003 examination results. The current research results demonstrated that while neither the RAPM nor the Organiser yielded any significant correlations with academic results, certain of the non-intellective measures did, and were able to differentiate between high and low academic performers. Motivation, Autonomy and Freedom from Anxiety were found to be significantly related to academic performance, and contributed 26 percent of the variance. This indicates that these factors play a role in academic achievement, and that exploration of personality and motivational factors constitutes a potentially fruitful avenue of research. However, it also seems that 74 percent of variance was unaccounted for, and therefore future studies should explore other factors, not included in this study, in relation to engineering students' academic performance. Furthermore, it emerged that it is unrealistic to attempt to predict academic performance at midyear (June results). KEY WORDS: Intelligence, learning strategies, locus of control, self-esteem, engineering students, second year, and academic performance. / AC2017
386

SYSTEMATIC LITERATURE REVIEW OF SAFETY-RELATED CHALLENGES FOR AUTONOMOUS SYSTEMS IN SAFETY-CRITICAL APPLICATIONS

Ojdanic, Milos January 2019 (has links)
An increased focus on the development of autonomous safety-critical systems requiresmore attention at ensuring safety of humans and the environment. The mainobjective of this thesis is to explore the state of the art and to identify the safetyrelatedchallenges being addressed for using autonomy in safety-critical systems. Inparticular, the thesis explores the nature of these challenges, the different autonomylevels they address and the type of safety measures as proposed solutions. Above all,we focus on the safety measures by a degree of adaptiveness, time of being activeand their ability of decision making. Collection of this information is performedby conducting a Systematic Literature Review of publications from the past 9 years.The results showed an increase in publications addressing challenges related to theuse of autonomy in safety-critical systems. We managed to identify four high-levelclasses of safety challenges. The results also indicate that the focus of research wason finding solutions for challenges related to full autonomous systems as well assolutions that are independent of the level of autonomy. Furthermore, consideringthe amount of publications, results show that non-learning solutions addressing theidentified safety challenges prevail over learning ones, active over passive solutionsand decisive over supportive solutions.
387

Stop being so informative! : A quantitative study on social media content and consumer engagement

Postnikova, Alena, Nilsson, Mathilda January 2019 (has links)
Purpose: Considering previous research on consumers’ social media engagement, content types and social media platforms, the purpose of this research was to explain the relationship between social media content types employed by brands and levels of consumers’ engagement. This since brands nowadays turn more towards branded content rather than advertising and several scholars expressing an urge for explaining an assumed relationship. Method: A deductive, quantitative and cross-sectional study was conducted. Further on, a standardized self-completion questionnaire was distributed to 227 respondents, by employing a convenience sampling. 165 responses were valid and the analysis was done employing ANOVA and regression analysis. Findings: Four hypotheses were accepted; all three concerning self-oriented content as it triggers all three levels of engagement and one hypothesis for entertaining content as it triggers emotional engagement. The hypothesis regarding the moderating effect of platform was partially accepted. Hence, five out of total ten hypothesis were rejected. Research limitations: The study’s generalizability is limited by the sampling technique and by the three example posts used in the questionnaire. Plus, the condition for respondents being exposed to social media post examples is another limitation in this research. Practical implications: All the findings were composed in a framework among of which is that brands’ content on social media should be of self-oriented nature to trigger engagement on all three levels or feature entertaining content as it triggers emotional engagement. YouTube is the preferred platform, followed by Instagram and then Facebook. However, all platforms trigger emotional engagement. The content benefits from being rich media and being appreciated by the consumers. Younger consumers are more likely to be engaged. Theoretical implications and originality: The findings of this research fill in the gap and present new findings within the topic of social media content, engagement and social media platforms. Hence, considering all the theoretical findings of this research, it offers a framework that delivers a rich explanation of relationships between social media content types, the three levels of engagement and social media platform types, which can be used as a base for further investigation in this area.
388

The Ever-Changing Personality: Revisiting the Concept of Triple-Loop Learning

Fahrenbach, Florian, Kragulj, Florian January 2019 (has links) (PDF)
Purpose - Considering personality as changeable through a bottom-up process of altering states, habits and traits, constitutes a shift in the predominant paradigm within personality psychology. The purpose of this paper is to reconsider Bateson's theory of learning and organizational triple-loop learning in light of this recent empirical evidence. Design/methodology/approach - This paper uses a multi-disciplinary conceptual approach. Based on an integrative analysis of literature from recent work in personality psychology, four dimensions (process, content, time and context) are identified that allow linking personality change and triple-loop learning. Findings - Identifying a bottom-up process of changing states, habits and traits as being central to change personality, allows for reconsidering Bateson's theory of learning as a theory of personality development (Learning II) and personality change (Learning III). Functionally equivalent, organizational triple-loop learning is conceptualized as a change in an organization's identity over time that may be facilitated through a change in responding to events and a change in the organization's routines. Practical implications - Interventions that change how organizations respond to events and that change the routines within an organization may be suitable to facilitate triple-loop learning in terms of changing organizational identity over time. Originality/value - This paper contributes to the discussion on Bateson's theory of learning and organizational triple-loop learning. As interest in personality change grows in organization studies, this paper aims to transfer these findings to organizational learning.
389

The cognitive processing potential of infants: a study of the effect of early infant exposure to numbers, shapes and colours

Van Vuuren, Jacqueline 02 1900 (has links)
Intellectual stimulation of young children is crucial, because it helps to break the cycle of poverty by giving each child the skills needed to reach his or her maximum potential. There is a growing need for more extensive early childhood development programmes in South Africa. Several studies in early childhood development have been shown to directly draw a parallel with enhanced student achievement at school and in life (Ackerman, 2005; Bueno, Darling-Hammond, & Gonzales 2010; Frede, Jung, Barnett, & Figueras, 2009). This study therefore explored the effects of an intervention programme introducing numbers, shapes and colours to infants between the ages of three months and 12 months. The sample consisted of 63 infants, with a control group of 34 and an experimental group of 29. The participants were selected from the middle-income group and consisted of infants from three different ethnic groups (black, white and coloured). Nine participants from the experimental group formed part of the focus group, which met every two weeks to give feedback and discuss the development of the infants and experiences of the parents involved in the intervention programme. In this study quantitative and qualitative data was collected. This data was assessed and analysed in order to achieve the four aims of the research study. The Bayley Scales of Infant Development (III) was used to assess three areas of development, namely cognitive ability, language skills and motor skills for the quantitative part of the study. The adaptive behaviour and social-emotional functioning of the infants was also assessed using the BSID (III), and this data was used in conjunction with the focus group feedback and problem-solving scenarios for the qualitative part of the study. Gender and the two age categories (3–7 and 8–12 months) for both the experimental and the control groups were examined and excluded from possible explanations for any significant findings. It was also determined that the control and experimental groups were well matched at the start of the intervention programme. The findings for aim A, the pre-test and post- test results showed that an average of 60 days involved in intervention programme had a statistically significant effect (z = -4.32, p < 0.001) on the cognitive ability of the infants. The findings for aim B, for the comparison between the control and experimental groups after the intervention programme, indicated significant results for the cognitive subscale (U = 732, p < 0.01, r = 0.42). Although the language and motor scores showed an increase in the descriptive statistics for the experimental group after the intervention, the Mann-Whitney U test did not show a significant difference. The findings for the qualitative study for aim C revealed that there was no effect on the adaptive behaviour of the infants. The findings for the social-emotional scales descriptive statistics for the qualitative study in aim D showed that there was a fairly large increase in the composite score means of the experimental group in comparison with the control group. The large increase in results complements the social-emotional functioning theme that emerged from the focus group. Three main themes emerged from the focus group, namely the cognitive ability, communication skills and social-emotional functioning of the infants.The increase in the social-emotional scale for the intervention group and the increase in the cognitive scale as mentioned in aim B were interrelated. These early social-emotional experiences are linked to long-term positive outcomes in both the social and cognitive areas of development (Landry, Smith, Swank, & Miller-Loncar, 2000). The parents all reported the ability to interpret the communication from their infants when participating in the flashcard sessions. This communication forms a foundation for establishing language development. Relationships between an infant’s nonverbal communication skills and subsequent language development have been reported (Brooks & Meltzoff, 2005). The problem-solving scenarios that were assessed during the second assessment showed that the infants who participated in the intervention programme were able to correctly identify a flashcard 73% of the time in comparison with the control group who were only able to identify a flashcard 1.4% correctly. The results of the study show that an early intervention programme has the potential to increase an infant’s cognitive ability and enhance his or her social-emotional functioning. However, the long-term impact of these findings would have to be explored in a longitudinal study. / Psychology / M.A. (Psychology)
390

Magnetotransporte em poços-quânticos de AlGaAs/GaAs com diferentes formas de potencial / Magnetotransport in AlGzAs/GzAs quantum wells with different potential shapes

Mamani, Niko Churata 18 August 2009 (has links)
Nesta tese, apresentamos estudos de magnetotransporte em poços quânticos duplos (DQWs) a campos magnéticos de baixo e sob a aplicação de um campo elétrico externo (potencial de porta). Medidas de magnetorresistência foram realizadas tanto no regime linear quanto no regime não linear. Relatamos a observação de oscilações magnéticas de inter-sub-banda (MIS) pela primeira vez. Estas oscilações MIS já foram estudadas em poços quânticos simples (QWs) com duas sub-bandas ocupadas; um DQW´e o sistema mais apropriado para o estudo das oscilações MIS. As oscilações MIS são atribuídas ao espalhamento inter-sub-banda, e a intensidade delas depende da largura da barreira (relacionada ao gap de energia entre as duas sub-bandas ocupadas, SAS). O estudo das oscilações MIS é uma ferramenta importante para poder acessar ao tempo de vida quântico dos elétrons a temperaturas onde as oscilações Shubnikov-de Haas (SdH) já não são observadas. Em nossas amostras, as oscilações MIS persistem até 25 K. Explicamos estes resultados num modelo teórico considerando um potencial de espalhamento de curto alcance com uma contribuição significativa do tempo de espalhamento elástico dos elétrons e uma contribuição do espalhamento elétron-elétron (e-e) com o aumento da temperatura. A aplicação de um campo elétrico externo (correntes dc) modifica fortemente as oscilações MIS. Descrevemos este efeito não linear causado pelo campo elétrico dc com uma função de distribuição oscilatória. Considerando o aquecimento dos elétrons pelo campo elétrico, é extraído o tempo de espalhamento inelástico. Para correntes dc grandes são encontradas discrepâncias entre o experimento e a teoria. Finalmente, consideramos medidas de magnetotransporte como função de potenciais de porta (porta na superficie) levando ao desbalance do DQW. Encontramos que as contribuições clássica e quântica são necessárias para a descrição teórica da magnetorresistência. Descrevemos as contribuições da magnetorresistência em termos das taxas de espalhamento inter e intra sub-banda utilizando uma função gaussiana como função da correlação do potencial. / In this thesis we present studies of magnetotransport in double quantum wells (DQWs) in low magnetic fields and under application of an external electric field (gate potential). Measurements of magnetoresistance have been carried out in both linear and non-linear regime. We report on the observation of magneto-intersubband (MIS) oscillations for the first time. These MIS oscillations have been studied already in quantum wells (QWs) with two occupied subbands, DQW is the most convenient system for studies of MIS oscillations. They are attributed to intersubband scattering and the strength of MIS oscillations depends on the barrier width (´delta´SAS). Analysis of MIS oscillations is an important tool to access quantum lifetime of electrons at high temperatures where Shubnikov-de Haas (SdH) oscillations are already absent. For our samples, MIS oscillations still exist up to 25 K. We explain these results in a theoretical model considering short-range scattering potential with a significant contribution of el´astic scattering time of electrons and a contribution of electron-electron (e-e) scattering if one increases temperature. Application of an external electric field (here a dc currents) strongly modifies the MIS oscillations. We describe this non-linear effect caused by a dc electric field with nonequilibrium part of the electron distribution function. Including the heating of electrons by the electric field, we are able to extract inelastic scattering time. For a strong dc current, a discrepancy between experiment and theory is found. Finally, we consider gate-dependent (top gate) magnetotransport measurements and drive de DQWs out of balance. We find that both cl´assical and quantum contributions are necessary for theoretical description of the magnetoresistance. We express both contributions in terms of inter and intrasubband scattering rates using a gaussian function as correlation function of the potential.

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