Devido à crescente demanda por perfis formados a frio destinados à fabricação de estruturas de aço no Brasil, aliada a desatualização da norma brasileira NB-143:1967, fez-se necessário a publicação de uma nova norma brasileira de \'Dimensionamento de Estruturas de Aço Constituídas por Perfis Formados a Frio\' a NBR14762:2001. Essa apresenta, para o dimensionamento das ligações, expressões adaptadas da norma norte-americana AISI:1996. As adaptações foram inseridas com o intuito de simplificar o cálculo e foram determinadas apenas por ajustes teóricos, faltando, portanto uma investigação mais criteriosa. Deste modo tornou-se prioritário o estudo das ligações em chapas e perfis com pequena espessura, para avaliação destas expressões propostas. Neste âmbito analisou-se neste trabalho o comportamento estrutural de ligações parafusadas em chapas e perfis formados a frio de pequena espessura, mediante análise teórica e experimental de corpos-de-prova, os quais foram definidos de maneira a se obter os diversos modos de falha, em especial a ruptura da seção líquida. Com os resultados experimentais pôde-se sugerir modificações nas expressões do coeficiente redutor da área líquida Ct, aplicado na avaliação da resistência ao estado limite de ruptura da seção líquida efetiva. Com os resultados desta pesquisa, espera-se colaborar com futuras edições da norma brasileira, fornecendo subsídios em suas futuras revisões. / The growing demand for cold-formed steel members of steel structures in Brazil, allied to the obsolescence of the brazilian NB-143:1967 standard, led to the need for a new brazilian code for the \'Design of Cold-formed Steel Structural Members\', the NBR14762:2001 standard. This new standard contains expressions adapted from the american AISI:1996 code for the design of connections. The adaptations were included with the purpose of simplifying the calculation and were determined merely for theoretical adjustments; hence, they lack a more careful investigation. It has thus become a matter of priority to study the connections in thin sheets and cold-formed members to evaluate the proposed expressions. The work reported on here therefore analyzed the structural behavior of bolted connections in thin sheets and cold-formed members based on theoretical and experimental analyses of test specimens, which were defined in order to obtain the various failure modes, particularly on sheet tearing in the net section. Based on the experimental results, suggestions are made for modifications in the expressions of the reduction coefficient of the net area Ct, applied in evaluations of the tensile strength of the effective net section. It is expected that the results of this research will contribute to future editions of the new brazilian code, supplying inputs for use in future revisions.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-09T15:24:44Z No. of bitstreams: 1 danielgustavomesquitadasilva.pdf: 1286713 bytes, checksum: 02c113ea7352199324c4ee67f18311bf (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-29T12:06:17Z (GMT) No. of bitstreams: 1 danielgustavomesquitadasilva.pdf: 1286713 bytes, checksum: 02c113ea7352199324c4ee67f18311bf (MD5) / Made available in DSpace on 2017-06-29T12:06:17Z (GMT). No. of bitstreams: 1 danielgustavomesquitadasilva.pdf: 1286713 bytes, checksum: 02c113ea7352199324c4ee67f18311bf (MD5) Previous issue date: 2009-04-06 / Neste trabalho foram obtidas Secções de Choque Totais Absolutas (SCTA) para moléculas de Etanol e Metanol utilizando um aparelho desenvolvido no Laboratório de Espectroscopia Atômica e Molecular do DF/UFJF, que emprega a técnica de transmissão linear. As medidas foram realizadas para o Metanol e Etanol cobrindo as energias de impacto de 70, 80, 90, 100, 150, 200, 250, 300, 350, 400 e 500 eV e também de 60 eV para o Etanol. A resolução de energia em todas as medidas foi de 0,6 eV (FWHM) e a incerteza no cálculo das SCTs foi estimada em 5%. A faixa de pressão na célula de espalhamento foi mantida entre 1 a 4mTorr. Os elétrons que sofreram processos de colisões inelásticas podem ser descriminados daqueles que não sofreram nenhum processo de interação com o alvo por um analisador cilíndrico dispersivo 127º, que tem a finalidade de selecionar os elétrons que serão detectados pelo Coletor de Faraday. Medindo a intensidade do feixe de elétrons atenuados, a SCTA pode ser obtida aplicando a Lei de Lambert Beer. Os dados foram obtidos através de um procedimento estatístico envolvendo uma série de 4 a 7 sessões de medidas, os valores obtidos foram utilizados para encontrar a SCT para uma determinada energia definida. Além das medidas experimentais, nós determinamos SCT utilizando a Regra da Aditividade. Nós também avaliamos nossos dados experimentais usando uma fórmula de dois parâmetros (Curva de Born) para cada gás. Nossos dados experimentais concordam com a maioria dos dados publicados na literatura. Não existem dados reportados na literatura de SCT para a molécula do Etanol (C2H5OH). / We have measured the absolute Total Cross Section (TCS) for methanol and ethanol molecules using an apparatus manufactured at the Molecular Spectroscopy Laboratory at DF/UFJF, which employ the linear transmission technique. The experimental data were taken at incident electron energies of 70, 80, 90, 100, 150, 200, 250, 300, 350, 400 and 500 eV for methanol and ethanol and also of 60 eV for ethanol. The energy resolution in all measurements was 0,6 eV (FWHM) and the overall systematic uncertainty at the TCS were evaluated to be less than 5%. The pressure range in the scattering cell was chosen between 1 and 4mTorr. Those electrons which passed the exit orifice of the chamber were discriminated with a 127o cylindrical energy selector coupled with an entrance set of electrostatic lenses and detected by a Faraday cup. Measuring the attenuation of intensity of the projectile-particle beam transmitted through the target volume, the absolute TCS for a given impact energy was derived from the Beer-Lambert law. The measurements were carried out for a given energy in a series of alt least 4 runs, each one taking at least 7 values and an averaging procedure was applied to derive the final total cross section at a particular energy. Besides the experimental measurements, we have additionally determined TCS using the Additivity Rule. We have also evaluated our experimental data using a fitting procedure with the Born-like formula containing two parameters for each gas. Our experimental data are in good agreement with the majority of previous measurements published in the literature. There are no previous reports of experimental electron scattering Total Cross Section C2H5OH in the literature.

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No. of bitstreams: 1 danielgustavomesquitadasilva.pdf: 3042917 bytes, checksum: 06395c899324e2d8dfd65fdbf105d471 (MD5) Previous issue date: 2018-06-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Valores precisos de Secção de Choque Total (SCT) para o espalhamento de elétrons por álcoois primários, como metanol, etanol, 1-propanol e 1- butanol, são muito importantes em muitas áreas aplicadas, uma vez que refletem a reatividade do alvo molecular no processo de colisão, como função da energia dos elétrons. Esses valores são muito úteis, por exemplo, quando se quer modelar a combustão do álcool no processo de ignição por centelha dentro de um motor de combustão interna. Através dessa modelagem, podemos melhorar o desempenho de veículos motorizados e de todas as tecnologias que utilizam atualmente combustíveis fósseis. Medidas de SCT absoluta para espalhamento de elétrons por moléculas do 1-propanol foram realizadas neste trabalho, para energias de impacto de 40 a 500 eV. Esses dados foram obtidos utilizando um novo aparelho desenvolvido neste trabalho, baseado na atenuação de um feixe de elétrons colimado através de uma célula gasosa que contém as moléculas a serem estudadas, a uma pressão e temperatura conhecidas. Este aparelho é constituído de um canhão de elétrons, uma célula gasosa, um analisador de energia de elétrons composto de um sistema de lentes eletrostáticas desaceleradoras seguido por um analisador cilíndrico dispersivo 127° (ACD 127°) e um coletor de Faraday. O aparelho está instalado dentro de uma câmara de vácuo coberta por 5 camadas de mu-metal, para blindagem de campos magnéticos espúrios, sendo diferencialmente bombeada através de duas bombas turbomoleculares; uma com velocidade de bombeamento de 80 l/s, para bombear a câmara do canhão de elétrons, a fim de evitar mudanças nas características de emissão do filamento quando o gás é introduzido na câmara; e a outra, com uma velocidade de bombeamento de 600 l/s, para bombear a célula de espalhamento e a região do analisador. O aparelho desenvolvido mostrou excelente desempenho, quando os dados de SCT por ele produzidos foram comparados com dados da literatura para os gases Ar, He, N2. Nossos dados experimentais de SCT para o 1-propanol, pelo melhor de nosso conhecimento, são os primeiros da literatura. Eles foram comparados com os resultados teóricos produzidos pelo Modelo do Átomo Independente Regra da Aditividade Revisada mais contribuições de interferências (MAIRAR+I), sendo verificada uma boa concordância. / Precise values of the Total Cross Section (TCS) for electron scattering by primary alcohols such as methanol, ethanol, 1-propanol and 1-butanol, are very important in many applied areas, given that the TCS reflects the reactivity of a molecular target in the collision processes as a function of the electron energy. These values are very useful, for instance, when modeling alcohol combustion through a spark ignition process within an internal combustion engines. Through this modeling we can improve the performance of motor vehicles, and all technologies currently utilizing fossil fuels. Absolute Total Cross Section (ATCS) measurements for electron scattering from 1-propanol molecules were obtained in this work, for impact energies from 40 to 500 eV. These data were obtained using a new apparatus developed in this work, which is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the molecules to be studied at a given pressure and temperature. This new apparatus consists of an electron gun, a gas cell, an electron energy analyzer composed of an array of decelerating electrostatic lenses, a cylindrical dispersive 127° analyzer (CDA 127°), and a Faraday cup. The apparatus is housed inside a vacuum chamber covered by 5 layers of mu-metal, for shielding against spurious magnetic fields, and differentially pumped through two turbomolecular pumps; one with a pumping speed of 80 l/s, for pumping the electron gun chamber in order to avoid changes in the electron emitting filament characteristics when gas is introduced into the chamber; and the other, with 600 l/s pumping speed, for pumping the scattering cell and analyzer region. The developed apparatus showed excellent performance when comparing our TCS data produced with it, with data from literature for the gases Ar, He, N2. Our TCS measurements for 1-propanol, to the best of our knowledge, are the first in the literature. These experimental measurements were compared with calculated TCS using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference (IAM-SCAR+I) approach with the level of agreement between them being typically found to be very good.

The transnational traffic of narcotics has had undeniable impacts on international development, for instance, stagnant economic growth in Myanmar (Chin, 2009), unsustainable agricultural practices in Yemen (Robins, 2016), and human security threats in Columbia (Thoumi, 2013). Furthermore, globalization is a catalyst for the transnational narcotics traffic (Robins, 2016; Aas, 2007; Kelly, Maghan & Serio, 2005). Several qualitative studies exist on the transnational narcotics traffic, yet few quantitative studies examine the issue. There is thus an opportunity for novel quantitative studies on the general question: “what are the main economic factors that influence the transnational traffic of narcotics between countries?” This study looked at the specific question: “are distance and economic size correlated with the volume of narcotics traffic between countries?” This study chose the gravity model as it centres on bilateral trade (Tinbergen, 1962), accounts for trade barriers (Kalirajan, 2008) and is empirically robust (Anderson 2011). This study defined a basic functional gravity model relating a proxy of the narcotics traffic to distance and economic size. Four augmented functional gravity models were also advanced to address omitted variable bias. The research was limited conceptually to cross sectional and pooled time series data. In addition, the data was also limited practically to a convenience sample of secondary data drawn from: the United Nations Office on Drugs and Crime’s (UNODC) (2016a) Individual Drug Seizures (IDS); the World Bank’s (2016) World Development Indicators; and the CEPII’s GeoDist (2016) datasets. This study used a novel “dosage” approach to unit standardization to overcome the challenge posed by the many measures and forms of narcotics. The study used the Poisson pseudo maximum likelihood (PPML) estimator as its estimations of the gravity model are consistent (Gourieroux et al., 1984), allow heteroscedasticity (Silva & Tenreyro, 2006) and avoid back transformation bias (Cox et al., 2008). The evidence analyzed in this study seem to indicate that the gravity model may not be applicable in its current form to the transnational narcotics traffic among countries that report drug seizures to the UNODC. However, the sampling method and the choice of proxy are likely to influence these findings. Moreover, the low explanatory power of the gravity model for the narcotics traffic, reflected in the values of the pseudo-R-squared coefficient of determination, indicates that other factors are at play. For instance, authors such as Asad and Harris (2003) and Thoumi (2003) argue that institutions could be a key factor in the narcotics traffic. Future empirical research into this topic could build on the theses findings to introduce new proxies and to explore alternate theoretical frameworks.

Nowadays, women have a wide range of sources of information about childbirth. Women's attitudes toward childbirth are made by sharing experiences between women and in families but also they are based on information from media and internet. Consequently attitudes toward childbirth influence the choice of kind of delivery and women's childbirth experience. These days we can see some trends in obstetrics - the rising interest in natural births, on the one hand, and the rising number of women delivering their babies by cesarean section on the other hand. The goal of this socio-psychologically oriented thesis is to map women's attitudes to these most striking birth trends, and also to identify the reasons for these women's attitudes. The research part is thus focused qualitatively and uses the data from the analysis of the internet discussion forums for mothers. In the previous theoretical part are presented the key information necessary to understand the studied topic, such as the issues of attitudes, the specifics of the communication on the internet discussion forums and above all the current scientific knowledge about the attitudes of women to childbirth in the Czech Republic and the world. Key words Attitudes of women, natural childbirth, assisted childbirth, homebirth, caesarean section, internet...

This work proposes a dynamic tool for solving the problem of fault section estimation in power systems. A Binary Integer Problem (BIP) is used to identify the faulty section trough analyses of circuit breakers states and power system protection devices signalizations. For the knowledge base construction it is proposed an innovative tool able to automatically generate the pattern of events and alarms for each topology configuration change. The outputs obtained from the pattern generator are used as base of cause end effect by the BIP model. Received alarms on SCADA are used as parameters in model the restrictions. The BIP model, based on the parsimonious set covering problem, is solved by CPLEX commercial software and it is able to deal with protection devices failure, data acquisition problems and occurrence of multiple events. To validate the approach it was used part of a brazilian power system, through the proposed technique the patterns were automatically generated and several faults situations were simulated. The proposed methodology achieved optimum results to all tests applied, being capable to deal with topology changes on power systems and with the problems inherent to the fault section estimation. / Este trabalho propõe uma ferramenta dinâmica para solução do problema de estimação da seção em falta em sistemas elétricos de potência. Um modelo de programação inteira binária (PIB) é usado para identificar a seção em falta através da análise do estado dos disjuntores e sinalizações de disparo das proteções de cada equipamento do sistema elétrico. Para a montagem da base de conhecimento é proposta uma ferramenta inovadora, capaz de gerar padrões de eventos e alarmes automaticamente, cada vez que a configuração da rede é alterada. O algoritmo usa como entrada o cadastro de conexões do sistema (secções e disjuntores) e a leitura do estado dos disjuntores. A saída obtida pelo gerador de padrões é usada como base de conhecimento pelo modelo de programação inteira binária. Os alarmes recebidos no SCADA são usados como parâmetros nas restrições do modelo. O modelo de PIB, fundamentado nos princípios de recobrimento parcimonioso de conjuntos, é resolvido através do otimizador comercial CPLEX, e é capaz de lidar com falhas nos dispositivos de proteção, problemas na aquisição de dados e múltiplas ocorrências. A metodologia foi validada tendo como base parte de um sistema elétrico de potência brasileiro, para o qual, por meio da técnica proposta, os padrões foram gerados automaticamente e simuladas diversas situações de faltas. A metodologia proposta apresentou ótimos resultados para todos os testes aplicados, sendo a ferramenta capaz de lidar com as alterações topológicas dos sistemas elétricos de potência e com os problemas inerentes à estimação da seção em falta.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis proposes an Intelligent Alarm Processor for fault diagnosis in electrical power systems. The objective is to develop a methodology for automatic fault analysis using reported alarms from Supervisory Control and Data Acquisition (SCADA) to allow the use of diagnosis systems in large power systems. The proposal can be used in real-time decision support systems to assist control center‟s operators during the decision-making after unscheduled contingencies with relevant information to power system restoration. This work expects to contribute to the development of advanced alarm management logics that allow modifying the chronological sequence of reported alarms, event mapping and the generation of operating patterns of protection systems according to topology network. Still, mathematical programming models have been formulated as a parsimonious set covering problem to fault section estimation and identification of protective devices with improper operation. Among these models, it stands out the model that deals with integrated analysis of reported alarms, events and diagnosis that better explain the alarms. The proposed approach has been tested in different portions of the Southern Brazilian power system. The results show that alarm processing allows the practical implementation of intelligent diagnosis methods in existing supervisory systems. The proposed diagnosis methods show better performance and accurate solutions than other methods presented in literature. / Esta tese propõe um Processador Inteligente de Alarmes para diagnóstico de faltas em sistemas elétricos de potência. O objetivo é desenvolver uma metodologia para a análise automática de faltas a partir dos alarmes reportados no sistema de supervisão e aquisição de dados (SCADA) que possibilite o uso de métodos de diagnóstico em sistemas de potência de grande porte. Essa proposta pode ser empregada em sistemas de apoio à decisão em tempo real, que auxiliem operadores de centros de controle do sistema (COS) na tomada de decisão após desligamentos não programados, com informações pertinentes para o restabelecimento do sistema. O trabalho espera contribuir com o desenvolvimento de lógicas avançadas de gerenciamento de alarmes que possibilitem a reordenação cronológica dos alarmes reportados, o mapeamento dos eventos e a geração de padrões de funcionamento de sistemas de proteção de acordo à topologia da rede. Além disso, os modelos de programação matemática foram formulados como um problema de recobrimento de conjuntos parcimonioso, para estimação da seção em falta e identificação dos dispositivos de proteção com atuação indevida. Dentre esses modelos, destaca-se o modelo que analisa, de forma integrada, os alarmes reportados e determina os eventos e diagnósticos que melhor explicam os alarmes. A abordagem proposta foi testada em diferentes porções do sistema sul do sistema interligado nacional (SIN). Os resultados mostram que as rotinas desenvolvidas para o processamento de alarmes permite a implantação prática de métodos inteligentes de diagnóstico em sistemas supervisórios existentes. Os métodos propostos para diagnóstico de faltas mostraram desempenhos e precisão nos resultados superiores a outros métodos presentes na literatura.

An environmentally sustainable production of electrical power is important for preserving the earth’s natural resources. In order to utilize this power as efficiently as possible, it is of great importance to minimize the losses, for example in sliding electrical contacts. A sliding electrical contact is where current is transferred from one rotating to one stationary component and power is lost due to friction and contact resistance. Also in some signal applications, high performance sliding contacts are crucial to ensure stable signal transfer with low noise. Although sliding electrical contacts are primarily designed for good electrical performance, the system will benefit also from optimization of the tribological properties. The aim of this thesis is to increase the fundamental knowledge of the tribological and electrical performance of metal-graphite composite materials for sliding electrical contacts. The influence of mechanical and electrical load was investigated. Different stationary materials, from pure copper to nanocomposite coatings, were tested against copper- and silver-graphites. Two complementary test setups were used, one with reciprocating and one with unidirectional sliding. Surface analysis was essential to gain deepened understanding of the influence of the interaction on the surfaces. Especially my novel imaging of cross-sections has advanced the level on knowledge in this research field. On the stationary material surface, a tribofilm forms with constituents from the metal-graphite and the surrounding atmosphere. Cross-sectioning reveals a material flow that indicates turbulence. Furthermore, the presence of oxides in the tribofilm is not necessarily detrimental for the contact resistance as long as there is also pure metal available. The presence of graphite is vital for low friction and wear. It is shown that the tribological and electrical behaviour of this system is only marginally influenced by the material selection of the stationary contact. Increasing the metal content in the composite, on the other hand, greatly reduces the contact resistance while there is no significant impact on friction and wear. The mechanical load has to be optimized to compromise between low wear (achieved with low load) and low contact resistance (achieved with high load). Pure mechanical tests show a lower friction and higher wear rate in comparison to tests with a five ampere current.

Background: Many women experience childbirth fear to such an extent that it seriously interferes with the woman’s daily life and affects her mental well-being. Aim: The overall aim was to conduct an overview of the midwife-led counselling for childbirth fear in Sweden, to investigate women’s birth preferences and to describe their experiences of treatment on childbirth fear, with focus on midwife-led counselling. Methods: Study I is a cross-sectional study where 43 out of 45 maternity clinics responded to a questionnaire regarding midwife-led counselling. Study II is a longitudinal survey where 889 women participated of whom 70 received counselling. Data were collected by questionnaires in mid-pregnancy, two months and finally, one year after birth. Study III is a randomised controlled study with 258 participating women assessed with childbirth fear. It compares Internet-based cognitive behaviour therapy (ICBT) with midwife-led counselling. Data were collected by questionnaires twice during pregnancy and two months after birth. Study IV is a qualitative interview study using thematic analysis, including 27 women who received midwife-led counselling during pregnancy. Results: Overall, midwife-led counselling was perceived as empowering by the women and increased their confidence when facing birth. The preference for a caesarean section decreased during pregnancy and the majority had a normal vaginal birth but an increase in preference for caesarean section appeared after birth. Half of the women who received treatment for childbirth fear experienced a less than positive birth. Women who had a positive birth experience voiced that the contributing factors were the self-confidence received from counselling and the support from the midwife during birth. Decreased or manageable fear was expressed by the women after counselling and birth, which in turn brought a strengthened confidence for a future pregnancy and birth. Furthermore, major differences exist in counselling for childbirth fear throughout the clinics in Sweden. Conclusion: Midwife-led counselling improved women’s confidence toward giving birth and fear was perceived as manageable. Continuous support is crucial to experience birth as positive. Although women’s preferences for caesarean section did not change over time, few women gave birth with a caesarean section without medial reason.

No abstract available. / Dissertation (MSc)--University of Pretoria, 1966. / gm2014 / Plant Science / Unrestricted