Abstract Background: ST-segment elevation myocardial infarction (STEMI) is the acute coronary syndrome with the highest severity and mortality. It can affect physical health and well-being of patients, and consequently their quality of life (QoL). Objective: To describe the QoL of patients at 30 days and 180 days after STEMI, focusing on sex differences and repercussions on physical and mental dimensions. Methods: Observational study with 174 STEMI patients included in the study on STEMI conducted in the city of Salvador, Brazil (PERSISST). The QoL of patients at 30 days (D30) and 180 days (D180) after the coronary event was assessed using the 12-item short form health survey (SF-12). Physical and mental components of QoL were calculated using the SF-12 OrthoToolKit. Descriptive analysis of data was made using the IBM SPSS software, version 25.0. Results: Mean age of participants at D30 and D180 was 57.1±11.4 years and 60.5±10.9 years, respectively, with a higher prevalence of men (55.8% and 56.8%). In general, patients had a poor QoL at both time points (scores 49.1±8.9 and 49.9±8.4, respectively). Analysis by sex, however, showed that men had a good QoL at both 30D (score 51.8±7.4) and 180 D (score 51.3±7.7), whereas a poor QoL was found among women at these time points (45.7±9.6 and 48.1±9.0, respectively). Men showed higher physical and mental health scale scores than women at both D30 and D180, and there was a greater impairment of the physical component in both sexes. Conclusion: Patients had poor QoL at 30 days and 180 days after STEMI, with a greater impairment of the physical component and a worse QoL perception among women than men at both time points.

Este artigo descreve a concepção e validação de um modelo matemático direcionado à soldagem GMAW. O modelo permite a predição de alguns parâmetros de soldagem, assim como o comportamento do processo em condições operacionais de transferência metálica por vôo livre. Este modelo foi baseado em um conjunto de equações, que descrevem as características operacionais da fonte de energia, as quedas de tensão que ocorrem no arco elétrico e nos componentes do circuito de soldagem, e em um balanço de energia na ponta do arame. A validação do modelo envolveu testes de soldagem mecanizada em corpos-de-prova de aço baixo carbono, com monitoração da corrente, tensão, comprimento de arco e velocidade de alimentação de arame. O modelo mostrou-se capaz de prever,em diferentes situações, com erros inferiores a 10%, os valores médios de alguns parâmetros fundamentais no processo de soldagem GMAW (valores médios de corrente, tensão e comprimento de arco elétrico), assim como, o comportamento destes na ocorrência de mudanças operacionais.

This paper describes the conception and validation of a mathematical model applied to GMA welding. This model allows predicting some welding parameters as well as process behavior for operation with free flight transfer mode. This model was based on a set of equations that describes the power source characteristics, the voltage drop along the electric arc, the welding circuit and the energy balance on the wire tip. The model validation was performed by comparing its results to experimental welding trials. In this test specimen steel of low carbon was used and the parameters welding current and voltage, speed of wire feeding and arc length were monitored. The results have shown that the model is able to correctly predict how different parameters change with alterations in wire feed, in different situations. Furthermore, welding current and voltage e arc length value were predicted with a least error lower than 10%.

O processo de soldagem GMAW é caracterizado por uma forte interdependência de seus parâmetros operacionais e uma grande sensibilidade a variações destes. Estas características podem causar variações nas condições operacionais, dificultando o estabelecimento e a reprodução destas condições que, usualmente precisam ser verificadas pela realização de testes. Como uma forma de minimizar esta dificuldade e facilitar o entendimento da relação entre as variáveis deste processo, tem-se trabalhado no desenvolvimento de um modelo matemático capaz de simular aspectos elétricos e operacionais da soldagem GMAW. O objetivo do presente trabalho foi estudar procedimentos de determinação e fatores que afetam duas variáveis fundamentais para o desenvolvimento deste modelo (a resistividade elétrica do arame durante a soldagem e a soma das quedas de tensão anódica e catódica no arco, U AC) na soldagem com transferência por curto-circuito. Os testes experimentais envolveram a deposição mecanizada de cordões emaço de baixo carbono usando arames do mesmo material com diferentes gases de proteção. Metodologias para a determinação dos parâmetros citados foram desenvolvidas com base em procedimentos similares indicados na literatura. Os detalhes destes procedimentos são avaliados, os resultados obtidos são comparados com dados da literatura e métodos para estimar a resistência elétrica entre o bico de contato e o eletrodo são apresentados. Os resultados sugerem valores para esta resistência entre 6 e 9 mΩ.

GMA welding is characterized by a strong dependence between its operational parameters and a high sensitivity to small variations of those. These characteristics tend to make it harder to replicate welding conditions. It is also a barrier to welding automation and makes it necessary to perform a number of real welding tests before determining operational conditions for a given application. In order to contribute to reduce these limitations of GMA welding, the authors of the present work have been working on the development of a mathematical model to simulate the variation of operational and electrical parameters during welding. This paper aims to evaluate methodologies to determine two key variables of this model (the electrode electrical resistivity and the sum of the voltage drops in the arc anode and cathode regions)in short-circuit welding. Experimental trials were performed in a mechanized jig by depositing bead-onplate welds on low-carbon steel bars. Methodologies to evaluate those variables were developed based in proposals from the literature. Experimental details of these methodologies are analyzed and their results are compared to results from the literature. These procedures are evaluated, compared with data from the literature and new procedures are proposed to estimate those parameters and the contact resistance between the contact tip and the electrode. Results suggest values between 6 and 9 Ω for this last parameter.