Material defect reconstruction by non-destructive testing with laser induced ultrasonics

Aligned with current research efforts and industrial applications on nondestructive testing, in this work, a hybrid system combining remotely induced laser ultrasonics with conventional transducer detection is studied for defects detection in metallic parts. The processing of the induced acoustic emission waves is proposed to be approached by means of a high-resolution volumetric signal processing procedure based on the synthetic aperture focusing technique for the benefit of the final 2D visualization of the defects. The advantages of the hybrid non-destructive testing approach and the performance of the processing technique are experimentally validated.Peer ReviewedPostprint (published version

Laser Ultrasound Inspection Based on Wavelet Transform and Data Clustering for Defect Estimation in Metallic Samples

Laser-generated ultrasound is a modern non-destructive testing technique. It has been investigated over recent years as an alternative to classical ultrasonic methods, mainly in industrial maintenance and quality control procedures. In this study, the detection and reconstruction of internal defects in a metallic sample is performed by means of a time-frequency analysis of ultrasonic waves generated by a laser-induced thermal mechanism. In the proposed methodology, we used wavelet transform due to its multi-resolution time frequency characteristics. In order to isolate and estimate the corresponding time of flight of eventual ultrasonic echoes related to internal defects, a density-based spatial clustering was applied to the resulting time frequency maps. Using the laser scan beam’s position, the ultrasonic transducer’s location and the echoes’ arrival times were determined, the estimation of the defect’s position was carried out afterwards. Finally, clustering algorithms were applied to the resulting geometric solutions from the set of the laser scan points which was proposed to obtain a two-dimensional projection of the defect outline over the scan plane. The study demonstrates that the proposed method of wavelet transform ultrasonic imaging can be effectively applied to detect and size internal defects without any reference information, which represents a valuable outcome for various applications in the industry. View Full-TextPeer ReviewedPostprint (published version

Diseño de investigación para la propuesta de un software para la mejora y automatización en la medición de la calidad de la energía de una subestación del sistema interconectado en Guatemala

Desarrollar un Software con la finalidad de mejorar y automatizar la medición en la calidad de la energía en una subestación eléctrica del sistema interconectado en Guatemala, así evaluar la regulación de voltaje y el desequilibrio de corriente con recomendaciones de software para detectar problemas en el sistema de transmisión de energía en la red y analizar la variación del factor de potencia en el sistema de transmisión de una línea de transmisión de 69 kV mediante la propuesta de un Software

Caracterización de defectos, diagnóstico y reparación de suelos de madera basado en un estudio de campo

A statistical characterization of defects in 35 buildings and 98 wood floorings (softwood and hardwood floors, and laminated and engineered wood floors), their diagnostic methods and repair solutions is presented. An expert system for inspecting wood flooring, comprising the classification of defects, their most probable causes, diagnostic methods and repair techniques, was used. Results include age, affected area, severity and frequency of defects and their main causes, as well as appropriate diagnostic methods, preventive and curative repair solutions most prescribed and the most significant correlations. Scratches were detected in more than five sixths of the sample, highly associated with exterior mechanical actions, and with an inadequate finishing layer. Wearing of the finishing layer was detected in a quarter of the inspected floorings. Accordingly, the application of a suitable finishing layer and, alternatively, its replacement are the most prescribed repair techniques.Se presenta una caracterización estadística de defectos en 35 edificios y 98 suelos de madera (sue-los de madera conífera y frondosa, pisos de madera laminada e de ingeniería de la madera), sus métodos de diagnóstico y soluciones de reparación. Se utilizó un sistema experto para inspeccionar suelos de madera, que incluía la clasificación de defectos, sus causas más probables, métodos de diagnóstico y técnicas de reparación. Los resultados incluyen edad, área afectada, gravedad y frecuencia de los defectos y sus principales causas, así como los métodos de diagnósticos apropiados, soluciones de reparación preventiva y curativa más prescritas y las correlaciones más significativas. Se detectaron arañazos en más de cinco sextos de la muestra, muy asociados con acciones mecánicas exteriores y con una capa de acabado inadecuada. El desgaste de la capa de acabado se detectó en un cuarto de los suelos inspeccionados. Por consiguiente, la aplicación de una capa de acabado adecuado y, en su caso, su sustitución son las técnicas de reparación más prescritas

O Conde do Farrobo a ação e o mecenato no século XIX

Tese apresentada para cumprimento dos requisitos necessários à obtenção do grau de Doutor em História e Teoria das IdeiasFigura expressiva e peculiar da sociedade de oitocentos, Joaquim Pedro Quintela do Farrobo, segundo barão de Quintela e primeiro conde do Farrobo, adquire especial projeção como mecenas no Portugal do Liberalismo. O cerne da problemática apresentada no âmbito deste trabalho de investigação, visa averiguar as principais ações e linhas de pensamento do conde, face a um pressuposto desenvolvimento cultural, tendo como pano de fundo as contradições e objetivos político-institucionais e particulares da época. Criando um espaço próprio, em que se adivinham as sementes do pensamento, e um projeto artístico e científico contemporâneos, na sua busca incessante da inovação, nunca perdendo de vista a seleção do melhor no legado do passado, o conde do Farrobo afirma-se como um dos mais importantes e significativos mecenas do final do século XIX

Waveguiding properties of a photonic crystal fiber with a solid core surrounded by four large air holes

The polarization-dependent guiding properties of a hexagonallattice photonic crystal fiber with a solid-core surrounded by four large air holes are investigated. The appearance of a polarization dependent cutoff frequency, together with several parameters as the birefringence, the modal effective area, the group velocity dispersion and the polarization dependent loss are analyzed. A collection of fibers with different structural parameters were fabricated and characterized. An effective anti-guide structure from at least 450 nm to 1750 nm, a polarizing fiber with a polarization dependent loss of 16 dB/m at 1550 nm, and an endlessly singlemode polarization maintaining fiber with group birefringence of 2.1x10-3 at 1550 nm are reported. Experimental results are compared with accurate numerical modeling of the fibers

Evaluación de escenarios de descenso energético para la transición ecológica

En este trabajo estableceremos el descenso en el consumo energético a nivel mundial que debe realizarse para afrontar la crisis ecológica actual. Evaluamos la desigualdad en el reparto del consumo energético y estableceremos cuál es el consumo mínimo para una vida digna. De esta forma lograremos establecer un umbral del descenso energético que sería universalizable para el conjunto de la población mundial, el cual ubicamos en un consumo anual de energía final per cápita de entre 15,6 GJ y 31,0 GJ para el año 2050. El consumo anual de energía final per cápita en promedio para Norte global se encontraba en 2017 en los 118 GJ. Posteriormente abordaremos las estrategias que son necesarias llevar a cabo para lograr estos descensos en los países del Norte global, comprendiendo la forma en la que se constituye la demanda y pasando de los enfoques basados en la eficiencia energética hacia aquellos basados en la suficiencia energética. Por último, realizamos un análisis de dos escenarios de transición ecológica en el estado español entre 2020 y 2030, Green New Deal y Decrecimiento. Adaptaremos el modelo de cálculo con el que se analizó previamente la evolución de horas de trabajo y emisiones para esos escenarios, y calcularemos las variaciones en el consumo energético. De esta forma obtenemos un consumo anual de energía final per cápita en 2030 de 44,6 GJ y 36,8 GJ para cada uno de los escenarios. Concluiremos evaluando estos resultados obtenidos con respecto al objetivo de descenso energético marcado por el umbral de consumo mínimo y consumo máximo.<br /

Analysis of medical opinions about the nonrealization of autopsies in a Mexican hospital using association rules and bayesian networks

This research identifies the factors influencing the reduction of autopsies in a hospital of Veracruz. The study is based on the application of data mining techniques such as association rules and Bayesian networks in data sets obtained from opinions of physicians. We analyzed, for the exploration and extraction of the knowledge, algorithms like Apriori, FPGrowth, PredictiveApriori, Tertius, J48, NaiveBayes, MultilayerPerceptron, and BayesNet, all of them provided by the API of WEKA. To generate mining models and present the new knowledge in natural language, we also developed a web application. The results presented in this study are those obtained from the best-evaluated algorithms, which have been validated by specialists in the field of patholog

Emotional strategies in physical education through learning service: application of the “feel while playing” program in primary students

Las emociones, la inteligencia emocional y la competencia socioemocional son algunos de los contenidos transversales que podemos desarrollar desde la Educación Física escolar. El juego motor es una fuente de estímulos y vivencias que favorece el desarrollo de las estructuras físicas y cerebrales que el alumnado de Primaria utilizará en su presente y futuro. El objeto de este estudio fue analizar las estrategias utilizadas para la resolución de conflictos tras la puesta en práctica de un programa de intervención denominado “Siente Jugando”, haciendo uso de la metodología Aprendizaje Servicio. La muestra estuvo formada por 93 participantes de Educación Primaria Obligatoria (EPO), de edades comprendidas entre los 6-8 años (41% chicas, 59% chicos) (48% de primer curso y 52% de segundo) y 50 participantes universitarios del segundo curso de Educación Infantil, quienes pusieron en práctica juegos que habían elaborado previamente para desarrollar los contenidos socioemocionales. Cada grupo desarrollaba las 6 emociones básicas y las 5 variables de la competencia (reconocimiento de emociones, autoconcepto, resolución de conflictos, conducta prosocial-altruista y empatía) durante 16 sesiones de 45 minutos (2 sesiones por semana). En los resultados, observamos un aumento significativo en el número de estrategias directas (p≤.000) e indirectas (p≤.000) tras la intervención. Sin embargo, aunque no encontramos diferencias estadísticamente significativas en el número de estrategias agresivas, a efectos prácticos sí observamos una disminución en los mismos, que repercutió en un aumento de aquellas directas e indirectas.Emotions, emotional intelligence and socio-emotional competence are some of the transversal contents that we can develop in Primary Education, in the subject of Physical Education. The motor game is a source of stimuli and experiences that encourages the development of physical and cerebral structures that the primary learning students will use in their present and future. The purpose of this study was to analyze the strategies used for the resolution of conflicts after putting into practice an intervention program called “Feel while Playing”, through the use of Service Learning methodology. The sample was formed by 93 participants of Compulsory Primary Education, aged between 6-8 years (41% girls, 59% boys) (48% of first grade and 52% of second grade) and 50 college Second year of Early Childhood Education, who put into practice games that had been previously elaborated to develop socio-emotional contents. Each group developed the 6 basic emotions and the 5 competence variables (recognition of emotions, self-concept, conflict resolution, prosocial-altruistic behavior and empathy) during 16 sessions of 45 minutes (2 sessions per week). In the results, we observed a significant increase in the number of direct (p≤.000) and indirect (p≤.000) strategies after the intervention. However, despite the fact that we did not find statistically significant differences in the number of aggressive strategies, we observed a decrease in them, which resulted in increased direct and indirect ones