Esta pesquisa apresenta uma metodologia, baseada em duas técnicas não invasivas para identificação e diagnóstico de pontos quentes em transformadores de potência durante plena operação ou em fase de projeto. A primeira técnica é baseada na medição de radiação infravermelha, emitida pelo equipamento em funcionamento e registrada por meio de análise termográfica. A segunda técnica é possível a partir do conhecimento prévio das características construtivas do transformador, fazendo uso do Método dos Elementos Finitos (MEF). A segunda técnica pode ser validada a partir das medições realizadas utilizando a primeira técnica. A formação de gases no interior dos transformadores de potência, devido à elevação da temperatura do óleo isolante em função dos pontos quentes, é discutida em detalhes com base nas normas técnicas estabelecidas pelo IEEE e IEC. As técnicas e procedimentos abordados ao longo dessa pesquisa foram obtidos a partir de um transformador com potência nominal de 120 MVA e relação de tensão 13,8/230 kV, projetado para integrar uma fazenda eólica ao Sistema Interligado Nacional (SIN). / This research presents a methodology based on two noninvasive techniques for identification and diagnostic of hot spots in power transformers during operation or project development. The first is based on measurements of infrared radiation from the equipment during operation and recording by thermography. The second technique is possible from the previous knowing of the constructive characteristics of the power transformer, by using the Finite Element Method (FEM). The second technique can be validated from measurements obtained using the first technique. The gas formation into the power transformers, because of the high temperatures in the insulating oil due to the hot spots, is discussed in details based on normative recommendations well established by the IEEE and IEC. All techniques and procedures to be approached in this research were obtained using a 120-MVA power transformer with voltage relationship of 13.8/230 kV that was projected to interconnect a wind farm to the Interconnected Brazilian System (Sistema Interligado Nacional - SIN).

O objetivo deste trabalho é analisar o Risco de Cárie através de variáveis microbiológicas: Risco Bacteriológico e da Resazurina (RB e RE); e de variáveis clínicas (superfícies de cárie, índice CPOS, manchas brancas e velocidade de fluxo salivar) designadas RF, num estudo longitudinal de 2 anos. A amostra inicial era de 97 escolares (11-13 anos) resgatando-se 55 ao final. Utilizou-se a técnica estatística Análise de Variância (ANOVA) e Comparações Múltiplas pelo Método de Tukey, com 5 por cento de significância, além do Teste de McNemar para verificar se RF era um bom triador dos grupos de risco. Os resultados mostraram que o teste RB (contagem de Streptococcus mutans na saliva) conseguiu determinar o grupo de alto risco que apresentou maior incidência de cáries. Este grupo foi melhor identificado quando a variável resposta foi incidência de cáries mais incidência de manchas brancas do que somente a incidência de cáries. Estes resultados foram semelhantes para RF. Não se conseguiu com RE, no entanto, diferenciar os grupos de risco ao nível de 5% de significância. Assim, conclui-se que tanto a variável microbiológica (RB) como as clínicas são bons parâmetros para determinar o grupo de alto risco de cárie. / The purpose of the present study was to analyse the Risk of Caries, through microbials variables - Bacteriology and Resazurin Risk (RB and RE); and clinical variables (RF) over a 2-yr period. Data are based on 97 school children (11-13 years old), recovering 55 at the final of the study. ANOVA and Tukey Test were applied at 5 per cent of significance, in addition the McNemar Test was applied to verify if RF was a good selector of the risk groups. The results showed that RB Test (number of Streptococcus mutans in saliva) identified people at higher risk of developing dental caries. This group was better identified when the resultant variable was incidence of caries plus incipient smooth surface lesions than only incidence of caries. These results were the same for RF. RE can\'t identify the groups of risk at 5 per cent of significance. It was concluded that both microbial (RB), and clinical variables were good parameters to identify people at high caries risk.

Esta pesquisa apresenta uma metodologia, baseada em duas técnicas não invasivas para identificação e diagnóstico de pontos quentes em transformadores de potência durante plena operação ou em fase de projeto. A primeira técnica é baseada na medição de radiação infravermelha, emitida pelo equipamento em funcionamento e registrada por meio de análise termográfica. A segunda técnica é possível a partir do conhecimento prévio das características construtivas do transformador, fazendo uso do Método dos Elementos Finitos (MEF). A segunda técnica pode ser validada a partir das medições realizadas utilizando a primeira técnica. A formação de gases no interior dos transformadores de potência, devido à elevação da temperatura do óleo isolante em função dos pontos quentes, é discutida em detalhes com base nas normas técnicas estabelecidas pelo IEEE e IEC. As técnicas e procedimentos abordados ao longo dessa pesquisa foram obtidos a partir de um transformador com potência nominal de 120 MVA e relação de tensão 13,8/230 kV, projetado para integrar uma fazenda eólica ao Sistema Interligado Nacional (SIN). / This research presents a methodology based on two noninvasive techniques for identification and diagnostic of hot spots in power transformers during operation or project development. The first is based on measurements of infrared radiation from the equipment during operation and recording by thermography. The second technique is possible from the previous knowing of the constructive characteristics of the power transformer, by using the Finite Element Method (FEM). The second technique can be validated from measurements obtained using the first technique. The gas formation into the power transformers, because of the high temperatures in the insulating oil due to the hot spots, is discussed in details based on normative recommendations well established by the IEEE and IEC. All techniques and procedures to be approached in this research were obtained using a 120-MVA power transformer with voltage relationship of 13.8/230 kV that was projected to interconnect a wind farm to the Interconnected Brazilian System (Sistema Interligado Nacional - SIN).

O objetivo deste trabalho é analisar o Risco de Cárie através de variáveis microbiológicas: Risco Bacteriológico e da Resazurina (RB e RE); e de variáveis clínicas (superfícies de cárie, índice CPOS, manchas brancas e velocidade de fluxo salivar) designadas RF, num estudo longitudinal de 2 anos. A amostra inicial era de 97 escolares (11-13 anos) resgatando-se 55 ao final. Utilizou-se a técnica estatística Análise de Variância (ANOVA) e Comparações Múltiplas pelo Método de Tukey, com 5 por cento de significância, além do Teste de McNemar para verificar se RF era um bom triador dos grupos de risco. Os resultados mostraram que o teste RB (contagem de Streptococcus mutans na saliva) conseguiu determinar o grupo de alto risco que apresentou maior incidência de cáries. Este grupo foi melhor identificado quando a variável resposta foi incidência de cáries mais incidência de manchas brancas do que somente a incidência de cáries. Estes resultados foram semelhantes para RF. Não se conseguiu com RE, no entanto, diferenciar os grupos de risco ao nível de 5% de significância. Assim, conclui-se que tanto a variável microbiológica (RB) como as clínicas são bons parâmetros para determinar o grupo de alto risco de cárie. / The purpose of the present study was to analyse the Risk of Caries, through microbials variables - Bacteriology and Resazurin Risk (RB and RE); and clinical variables (RF) over a 2-yr period. Data are based on 97 school children (11-13 years old), recovering 55 at the final of the study. ANOVA and Tukey Test were applied at 5 per cent of significance, in addition the McNemar Test was applied to verify if RF was a good selector of the risk groups. The results showed that RB Test (number of Streptococcus mutans in saliva) identified people at higher risk of developing dental caries. This group was better identified when the resultant variable was incidence of caries plus incipient smooth surface lesions than only incidence of caries. These results were the same for RF. RE can\'t identify the groups of risk at 5 per cent of significance. It was concluded that both microbial (RB), and clinical variables were good parameters to identify people at high caries risk.

Concern about environmental injustice has been driving the recent effort to characterize risks from exposures to air toxics at very fine spatial resolutions. However, few studies seek to understand the potential policy implications of regulating risks at increasingly finer spatial resolutions and the impact of resulting policies on distribution of risks. To address this gap, the broad question for this research is how could the choice of spatial resolution for regulation of risks from toxic air pollutants affect emission controls and the consequences thereof? This research develops a formal model of a hypothetical decision maker choosing emission controls within a risk-based regulatory framework. The model suggests that optimal controls on air toxics emissions vary depending on the spatial resolution chosen to regulate risks; net social costs are non-decreasing as one regulates at finer and finer spatial resolutions. An empirical application of the model using air toxic emission data for Escambia and Santa Rosa Counties in Florida demonstrates the sensitivity of optimal emissions to spatial resolution chosen for regulation. The research then investigates the equity implications of regulating at different spatial resolutions with regard to the spatial distribution of cancer risks. The empirical results indicate that regulation at finer spatial resolutions could involve a tradeoff between costs and equitable distribution of risks. For example, at a threshold cancer risk of 100 in a million, regulating at census block level resolution could be twice as costly as regulating at census tract resolution while reducing the maximum individual risk by almost half. Further, regulation at finer spatial resolutions might not address environmental injustice by itself unless such concerns are more explicitly incorporated into emission control decisions. Finally, this research shows that spatial resolution at which air toxics risks are regulated could matter in predictable ways even after taking into account the uncertainties that the decision maker faces.

Collisions between personnel on foot and heavy equipment or materials on a construction site can be characterized as a contact collision. These types of incidents are a common occurrence on a work site. Technology is needed to improve work zone safety by alerting workers that are in danger of collisions pro-actively and in real-time. Developing this technology may assist in collecting previously un-recorded data on "near-misses" (close-calls). An approach is presented in this paper that is based on wireless radio frequency technology to alert workers in real-time when they are in danger. Various experiments are described that have been conducted in order to gain better understanding of the technology's potential, including measuring equipment blind spots and alert (or safety) zones. Blind spots areas are measured for six common construction vehicles to help determine the required (or minimum) alert distance (safety zone) for the equipment. A computer program was developed in-house to automatically calculate the percentage of blind spots on 2-dimensional planes and in the overall 3-dimensional volume. The blind spots results directly indicate the necessary safety zones for the equipment. The proximity device results show that technology demonstrated the capability of collecting important safety data while pro-actively detecting hazardous situations and warning workers and equipment operators during imminent potential hazardous events. Furthermore, the presented research can lead to improve the overall safety performance in construction and elsewhere through improved learning and education by providing relevant information to decision makers at all levels.

All modern High Temperature Reactors (HTR) thermal cycles have one thing in common: the use of some form of heat exchanger. This heat exchanger is used to pre-heat or cool the primary loop gas, from where the secondary power generation cycle is driven. The Compact Heat Exchanger (CHE) type offers high heat loads in smaller volumes. Various studies have been done to improve the heat transfer in the flow channels of these CHEs but little focus has been placed on the thermal design of surrounding material in such a heat exchanger. The focus of this study is on the effective material usage in a CHE. Three test cases were investigated (trapezoidal, serpentine and zigzag layouts with semi-circular cross-sections) all under the same boundary conditions. Computational Fluid Dynamics (CFD) was used to simulate these test cases and the results were evaluated according to four factors, the volume ratio, heat spots, temperature difference and the combined enhancement factor. From the results it was concluded that the zigzag layout performs best when evaluated according to the volume ratio and the temperature difference and gave the best overall enhancement factor. The serpentine layout performed the worst when evaluated according to the enhancement factor. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013

All modern High Temperature Reactors (HTR) thermal cycles have one thing in common: the use of some form of heat exchanger. This heat exchanger is used to pre-heat or cool the primary loop gas, from where the secondary power generation cycle is driven. The Compact Heat Exchanger (CHE) type offers high heat loads in smaller volumes. Various studies have been done to improve the heat transfer in the flow channels of these CHEs but little focus has been placed on the thermal design of surrounding material in such a heat exchanger. The focus of this study is on the effective material usage in a CHE. Three test cases were investigated (trapezoidal, serpentine and zigzag layouts with semi-circular cross-sections) all under the same boundary conditions. Computational Fluid Dynamics (CFD) was used to simulate these test cases and the results were evaluated according to four factors, the volume ratio, heat spots, temperature difference and the combined enhancement factor. From the results it was concluded that the zigzag layout performs best when evaluated according to the volume ratio and the temperature difference and gave the best overall enhancement factor. The serpentine layout performed the worst when evaluated according to the enhancement factor. / Thesis (MIng (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013

I concern on african mouthbrooding fishes (Cichlidae) and the possible role of egg-dummies during their courtship (Wickler's theory). I am bringing list of african cichlid fishes with information about kind of parental care, courtship ritual and presence of egg-dummies and I am giving this ethoecological information to phylogenetic context.

In this paper I focused on the examination of chosen localities inside the hybrid zone of the fire-bellied toads, where the occurrence of these species and their hybrids was confirmed in previous research. The goal is to follow the development of these habitats, suitable for the presence of a threatened species, and trends in quantities of these toads. Another aim was to calculate the hybrid index of each individual based on the ventral spots and so to classify the populations on each locality according to species.