Environmentally Assisted Cracking Behavior of S420 and X80 Steels Containing U-notches at Two DifferentCathodic Polarization Levels: An Approach from the Theory of Critical Distances

This paper analyzes, using the theory of critical distances, the environmentally assisted cracking behavior of two steels (S420 and API X80) subjected to two different aggressive environments. The propagation threshold for environmentally assisted cracking (i.e., the stress intensity factor above which crack propagation initiates) in cracked and notched specimens (KIEAC and KN IEAC) has been experimentally obtained under di erent environmental conditions. Cathodic polarization has been employed to generate the aggressive environments, at 1 and 5 mA/cm2, causing hydrogen embrittlement on the steels. The point method and the line method, both belonging to the theory of critical distances, have been applied to verify their capacity to predict the initiation of crack propagation. The results demonstrate the capacity of the theory of critical distances to predict the crack propagation onset under the di erent combinations of material and aggressive environments.The authors of this work would like to express their gratitude to the Spanish Ministry of Science and Innovation for the financial support of the projects MAT2014-58738-C3-3-R and MAT2014-58443-P developed by the University of Cantabria

Critical distance default values for structural steels and a simple formulation to estimate the apparent fracture toughness in u-notched conditions

The structural integrity assessment of components containing notch-type defects has been the subject of extensive research in the last few decades. The assumption that notches behave as cracks is generally too conservative, making it necessary to develop assessment methodologies that consider the specific nature of notches, providing accurate safe predictions of failure loads or defect sizes. Among the different theories or models that have been developed to address this issue the Theory of Critical Distances (TCD) is one of the most widely applied and extended. This theory is actually a group of methodologies that have in common the use of the material toughness and a length parameter that depends on the material (the critical distance; L). This length parameter requires calibration in those situations where there is a certain non-linear behavior on the micro or the macro scale. This calibration process constitutes the main practical barrier for an extensive use of the TCD in structural steels. The main purpose of this paper is to provide, through a set of proposed default values, a simple methodology to accurately estimate both the critical distance of structural steels and the corresponding apparent fracture toughness predictions derived from the TCD.The authors of this work would like to express their gratitude to the Spanish Ministry of Science and Innovation for the financial support of the Project MAT2014-58443-P: “Análisis del comportamiento en fractura de componentes estructurales con defectos en condiciones de bajo confinamiento tensional”, on the results of which this paper is based

Planteamiento de una metodología de análisis de la fisuración asistida por el ambiente de acero X80 basada en la teoría de las distancias críticas

Este trabajo presenta un análisis de la fisuración asistida por ambiente empleando la Teoría de las Distancias Críticas (TDC). La investigación se desarrolla a través de un programa experimental compuesto de probetas C(T) de fractura con diferentes radios de entalla, desde 0 mm (defecto tipo fisura) hasta 2 mm. El material utilizado es un acero X80 utilizado en tuberías de transporte de gas a bajas temperaturas que ha sido estudiado en condiciones de Fragilización por Hidrógeno (FH). El trabajo se completa con simulaciones por Elementos Finitos. En base a los resultados, la capacidad de la TDC para analizar procesos de fisuración asistida por ambiente queda probada en este material y en las condiciones estudiadas.Los autores desean agradecer al Ministerio de Economía y Competitividad la financiación recibida de los proyectos MAT2014-58443-P y MAT2014-58738-C3-3- R desarrollado por la Universidad de Cantabria

Application of the incremental step loading technique to Small Punch Tests on S420 steel in acid environments

ABSTRACT: The Small Punch test has been recently used to estimate mechanical properties of steels in aggressive environments. This technique, very interesting when there is shortage of material, consists in using a small plane specimen and punch it until it fails. The type of tests normally used are under a constant load in an aggressive environment, with the target to determine the threshold stress. However, this is an inaccurate technique which takes time, as the tests are quite slow. In this paper, the Small Punch tests are combined with the step loading technique collected in the standard ASTM F1624 [1] to obtain the value of threshold stress of an S420 steel in a total time of approximately one week. The ASTM F1624 indicates how to apply constant load steps in hydrogen embrittlement environments, increasing them subsequently and adapting their duration until the specimen fails. The environment is created by means of cathodic polarization of cylindrical tensile specimens in an acid electrolyte. A batch of standard tests are performed to validate the methodology.The present work was performed in the University of Cantabria, through the post-doctoral contracts program (budgetary application 62.0000.64251), and supported by the Government of Cantabria and the University of Cantabria in the framework of “Proyectos Puente 2019” call

Valores por defecto de la distancia crítica en aceros estructurales. Estimaciones de la tenacidad aparente a fractura en presencia de entallas en U

La evaluación de integridad estructural de componentes con defectos tipo entalla ha sido objeto de una extensa investigación en las últimas décadas. La asunción de que las entallas se comportan como fisuras es generalmente muy conservadora, haciendo necesario desarrollar metodologías de análisis que consideren la naturaleza específica de las entallas, de tal forma que se obtengan predicciones seguras y precisas de las cargas de rotura o del tamaño del defecto. Entre las diferentes teorías o modelos que se han desarrollado para abordar este tema, la Teoría de las Distancias Críticas (TDC) es una de las más aplicadas y extendidas. Esta teoría es realmente un grupo de metodologías que tienen en común el uso de la tenacidad del material y un parámetro de longitud que depende del material (la distancia crítica, L). Este parámetro de longitud requiere calibración en aquellas situaciones en las que haya comportamiento no lineal, tanto en la escala micro como en la macro. Este proceso de calibración constituye la principal barrera práctica para el uso frecuente de la TDC en aceros estructurales. La principal propuesta de este artículo es proveer a través de un conjunto de valores por defecto propuestos, una metodología para estimar de forma precisa tanto la distancia crítica en aceros estructurales a temperaturas de la zona de transición como la tenacidad aparente a fractura derivada del uso de la TDC.MAT2014-58443-

Automatic generation of models for abdominal aortic aneurysms and intraluminal thrombus based on hexahedral meshes

To propose an automated patient-specific algorithm for the creation of accurate and smooth meshes of the aortic anatomy, to be used for evaluating rupture risk factors of abdominal aortic aneurysms (AAA). Finite element (FE) analyses and simulations require meshes to be smooth and anatomically accurate, capturing both the artery wall and the intraluminal thrombus (ILT). The two main difficulties are the modeling of the arterial bifurcations, and of the ILT, which has an arbitrary shape that is conforming to the aortic wall

Motivación hacia el ejercicio en estudiantes universitarios, diferencias demográficas

During the study, the motivation towards the exercise of students of the Sports Training Bachelor program (Licenciatura en Entrenamiento Deportivo, LED) was analyzed. Supported by the Self-determination Theory (SDT; Deci & Ryan, 1985; 2002). The objective was to compare the motivational regulations towards exercise based on sex, work situation and semester in college students. Data was collected from 260 students of both sexes (172 men and 88 women), aged from 19 to 32 years (M = 22.11, SD = 2.19), all completed the Exercise Behavior Regulation Questionnaire (BREQ-3; Zamarripa et al., 2018). An association (p <.01) between the most self-determined regulations (intrinsic, integrated and identified) with introjected regulation was evidenced. The less self-determined regulations (external and non-motivational) are positively associated with each other, and negatively with the more self-determined. Small but significant effects of demographic indicators on motivational regulations (p <.05), men present higher values in integrated, identified, introjected and non-motivated regulations regarding sex; working students present higher values in integrated and identified regulations regarding employment status; and second cycle students present higher values in introjected regulation by semester cycle. In conclusion, reliability of the Mexican version of the BREQ-3 is confirmed, supporting the predictions of the SDT continuum. Demographic indicators effect may be mediated by sociocultural premises, so further research is suggested for conclusive results.El estudio analizó la motivación hacia la práctica del ejercicio de estudiantes de la Licenciatura en Entrenamiento Deportivo (LED). Soportado por la Teoría de la autodeterminación (TAD; Deci & Ryan, 1985; 2002), el objetivo fue comparar las regulaciones motivacionales hacia el ejercicio en función del sexo, situación laboral y semestre cursado en estudiantes universitarios. Se recolectaron datos de 260 estudiantes de ambos sexos (172 hombres y 88 mujeres), con edades entre 19 a 32 años (M = 22.11, DT = 2.19), todos completaron el Cuestionario de Regulación de la Conducta en el Ejercicio (BREQ-3; Zamarripa et al., 2018). Se evidenció asociación (p < .01), entre las regulaciones más autodeterminadas (intrínseca, integrada e identificada) con la regulación introyectada. Las regulaciones menos autodeterminadas (externa y no motivación) se asocian positivamente entre sí, y negativamente con las más autodeterminadas. Se observaron efectos pequeños pero significativos de los indicadores demográficos en las regulaciones motivacionales (p < .05), hombres presentan mayores valores en las regulaciones integrada, identificada, introyectada y no motivación con respecto al género; estudiantes que trabajan presentan mayores valores en las regulaciones integrada e identificada con respecto a situación laboral; y estudiantes del segundo ciclo presentan mayores valores en la regulación introyectada con relación a ciclo cursado. En conclusión, se confirma la confiabilidad de la versión mexicana BREQ-3, apoyando la predicción del continuo de la TAD. El efecto de los indicadores demográficos pudiera estar mediado por premisas socioculturales, por lo que se sugiere continuar con una mayor investigación para obtener resultados concluyentes

Study protocol for an observational cohort evaluating incidence and clinical relevance of perioperative elevation of high-sensitivity troponin I and N-terminal pro-brain natriuretic peptide in patients undergoing lung resection

INTRODUCTION: Myocardial injury after non-cardiac surgery has been defined as myocardial injury due to ischaemia, with or without additional symptoms or ECG changes occurring during or within 30 days after non-cardiac surgery and mainly diagnosed based on elevated postoperative cardiac troponin (cTn) values. In patients undergoing thoracic surgery for lung resection, only postoperative cTn elevations are seemingly not enough as an independent predictor of cardiovascular complications. After lung resection, troponin elevations may be regulated by mechanisms other than myocardial ischaemia. The combination of perioperative natriuretic peptide measurement together with high-sensitivity cTns may help to identify changes in ventricular function during thoracic surgery. Integrating both cardiac biomarkers may improve the predictive value for cardiovascular complications after lung resection. We designed our cohort study to evaluate perioperative elevation of both high-sensitivity troponin I (hs-TnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients undergoing lung resection and to establish a risk score for major cardiovascular postoperative complications. METHODS AND ANALYSIS: We will conduct a prospective, multicentre, observational cohort study, including 345 patients undergoing elective thoracic surgery for lung resection. Cardiac biomarkers such as hs-TnI and NT-proBNP will be measured preoperatively and at postoperatively on days 1 and 2. We will calculate a risk score for major cardiovascular postoperative complications based on both biomarkers' perioperative changes. All patients will be followed up for 30 days after surgery. ETHICS AND DISSEMINATION: All participating centres were approved by the Ethics Research Committee. Written informed consent is required for all patients before inclusion. Results will be disseminated through publication in peer-reviewed journals and presentations at national or international conference meetings. TRIAL REGISTRATION NUMBER: NCT04749212

Deepint.net: A rapid deployment platform for smart territories

This paper presents an efficient cyberphysical platform for the smart management of smart territories. It is efficient because it facilitates the implementation of data acquisition and data management methods, as well as data representation and dashboard configuration. The platform allows for the use of any type of data source, ranging from the measurements of a multi-functional IoT sensing devices to relational and non-relational databases. It is also smart because it incorporates a complete artificial intelligence suit for data analysis; it includes techniques for data classification, clustering, forecasting, optimization, visualization, etc. It is also compatible with the edge computing concept, allowing for the distribution of intelligence and the use of intelligent sensors. The concept of smart cities is evolving and adapting to new applications; the trend to create intelligent neighbourhoods, districts or territories is becoming increasingly popular, as opposed to the previous approach of managing an entire megacity. In this paper, the platform is presented, and its architecture and functionalities are described. Moreover, its operation has been validated in a case study where the bike renting service of Paris—Vélib’ Métropole has been managed. This platform could enable smart territories to develop adapted knowledge management systems, adapt them to new requirements and to use multiple types of data, and execute efficient computational and artificial intelligence algorithms. The platform optimizes the decisions taken by human experts through explainable artificial intelligence models that obtain data from IoT sensors, databases, the Internet, etc. The global intelligence of the platform could potentially coordinate its decision-making processes with intelligent nodes installed in the edge, which would use the most advanced data processing techniques.This work has been partially supported by the European Regional Development Fund (ERDF) through the Interreg Spain-Portugal V-A Program (POCTEP) under grant 0677_DISRUPTIVE_2_E, the project My-TRAC: My TRAvel Companion (H2020-S2RJU-2017), the project LAPASSION, CITIES (CYTED 518RT0558) and the company DCSC. Pablo Chamoso’s research work has been funded through the Santander Iberoamerican Research Grants, call 2020/2021, under the direction of Paulo Novais

Risk behaviors of 15–21 year olds in Mexico lead to a high prevalence of sexually transmitted infections: results of a survey in disadvantaged urban areas

BACKGROUND: Due to the fact that adolescents are more likely to participate in high-risk behaviors, this sector of the population is particularly vulnerable to contracting sexually transmitted infections (STIs) and resultant health problems. METHODS: A survey was carried out among adolescents from poor homes in 204 small-urban areas of Mexico. Information was collected in relation to risk behaviors and socio-economic environment. A sub-group of the participants also provided blood and urine samples which were analyzed to detect sexually transmitted infections. RESULTS: The presence of Chlamydia was detected in nearly 8% of participants who had stated that they were sexually active (18%) and approximately 12% were positive for herpes type 2-specific antibodies. For both, a greater proportion of girls resulted positive compared to boys. The presence of these biological outcomes of sexual risk behavior was associated with other risk behaviors (smoking), but not with self-reported indicators of protected sex (reported use of condom during most recent sexual activity). CONCLUSION: The results presented in this study show a startlingly high prevalence of HSV-2 among sexually active Mexican adolescents in poor urban areas, suggesting that this group has participated to a great extent in risky sexual practices. The relationships between socioeconomic environment and adolescent risk behavior need to be better understood if we are to design preventive interventions that modify the determinants of risk behaviors