Análisis de elemento finito y rediseño mecánico de una Boya Oceanográfica y de Meteorología Marina del CIGoM

Proyecto de Graduación (Licenciatura en Mantenimiento Industrial) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Electromecánica, 2021El Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), en colaboración con el Consorcio de Investigación del Golfo de México (CIGoM), diseñaron y manufacturaron un conjunto de Boyas Oceanográficas y de Meteorología Marina (BOMM) para el estudio de las condiciones ambientales en la región del Golfo de México como parte de su línea de investigación: plataformas de observación oceanográficas. Luego de aproximadamente seis meses de operación en las costas de Veracruz, la unidad BOMM-VER-2 muestra evidencia de fracturas en soldaduras y elementos estructurales en una de las secciones de la boya, las cuales comprometen su operatividad y la seguridad de los equipos instalados en la plataforma. Este trabajo final de graduación consiste en el estudio de esfuerzos mecánicos por medio del método de Análisis de Elementos Finitos (FEA) presentes en la BOMM-VER-2, con el fin de entender el comportamiento de la estructura mecánica de la boya bajo condiciones nominales de operación en el Golfo de México e identificar las condiciones potenciales que pueden ocasionar fallas estructurales. Para llevar a cabo la investigación, se tomaron en cuenta el viento, la corriente y el oleaje en la costa de Veracruz como condiciones ambientales de diseño. Se calculó la fuerza que ejercen estos fenómenos sobre la BOMM por medios analíticos y se validaron haciendo uso de la Dinámica Computacional de Fluidos (CFD). Adicionalmente, se analizaron diversas mejoras de diseño estructural para evitar la formación de fracturas en la plataforma durante su funcionamiento. Como resultados, se obtiene un mapa de esfuerzos estáticos de la BOMM durante su operación donde se muestran las secciones que soportan mayor carga y un rediseño geométrico que reduce el máximo esfuerzo presente en la estructura en un 31 %.Centro de Investigación Científica y Educación Superior de Ensenada (CICESE), in collaboration with Consorcio de Investigación del Golfo de México (CIGoM), manufactured a set of Oceanographic and Marine Meteorological Buoys (BOMM) for the study of environmental conditions in the Gulf of Mexico region as part of their research line: oceanographic observation platforms. After approximately six months of operation off the coast of Veracruz, the BOMM-VER-2 unit shows evidence of fractures in welds and structural elements in one of the buoy sections, which compromise its operability and the safety of the equipment installed on the platform. This final graduation work consists of the study of mechanical stresses by means of the Finite Element Analysis (FEA) method present in the BOMM-VER-2, to understand the behavior of the buoy's mechanical structure under nominal operating conditions in the Gulf of Mexico and to identify potential conditions that may cause structural failures. For this purpose, static, fatigue and welding tests were performed in SolidWorks design software. For the study, wind, current and tidal phenomena were considered as environmental design conditions. The force exerted by these phenomena on the BOMM was calculated by analytical means and validated using Computational Fluid Dynamics (CFD). Additionally, structural design alternatives were carried out to avoid the formation of fractures in the platform during its operation. As a result, a static stress map of the BOMM during its operation is obtained, showing the sections that support the highest load and a geometric redesign that reduces the maximum stress present in the structure by up to 31%

¿Quién se ha sentido así? Fomentando la vulnerabilidad y la esperanza transformadora en el conocimiento activista del Grado de Estudios Ingleses

Memoria ID2022-112. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2022-2023

On the origin of remanence enhancement in exchange-uncoupled CoFe2O4-based composites

© 2014 AIP Publishing LLC. Abundant efforts are being devoted to the production of nanostructured composites based on ferrites where the exchange-spring mechanism yields larger energy products. However, experimental results occasionally contradict the predictions, and the origin of the phenomenology is not always thoroughly understood. Magnetic properties may eventually evolve in trends similar to that of exchange-spring magnets due to structural changes unrelated to exchange-coupling mechanisms at hard/soft interfaces. Thus, the evaluation of the possible sources of magnetic improvement is pivotal in determining and optimizing the extent of exchange-coupling in spring magnets. Here, we report the observation of remanence improvement and single-phase reversal behavior at room-temperature in CoFe2O4/FeCo composites, where the hard and soft phases are predominantly uncoupled. The results are explained in terms of the temperature evolution of the individual properties of CoFe2O4. Causes for the observation of single-phase magnetization reversal in exchange-uncoupled systems are discussed. Our results indicate that these type of phenomena must be taken into account in order to thoroughly understand the optimization required to improve the magnetic performance of CoFe2O4-based composites.Peer Reviewe

Recovering Polyphenols in Aqueous Solutions from Olive Mill Wastewater and Olive Leaf for Biological Applications

Olive leaf and olive mill wastewater are wastes which are produced in olive industry and can be used to obtain value-added products such as polyphenols. In this work, extracts of polyphenols from olive mill wastewater and olive leaf in an aqueous medium are obtained and their composition in polyphenols were determined and compared with those obtained using the conventional extract agent (methanol–water). The antioxidant capacity of the aqueous extracts of olive mill wastewater and olive leaf were also analysed. It was observed that the olive mill wastewater extracted in water provides a similar content of phenolic compounds in the final extract compared to extraction with methanol–water, with the main polyphenols being hydrotyrosol and tyrosol (20.1 and 6.61 mg gdw−1). In the case of leaf extraction, the methanol-free extract (recovery in water after extraction with methanol–water) had a lower total phenol content compared to the methanolic extract, with the main polyphenol being oleuropein (22.73 and 9.05 mg gdw−1, for the methanol and methanol-free extract, respectively). However, both extracts obtained in aqueous solution present a similar antioxidant capacity at very diluted concentrations of the original extract, with IC50 values (half-maximal antioxidant concentration) of about 20 mg TS L−1. The antioxidant capacity of the extract in aqueous solution facilitates its application as an antioxidant in biological systems, like animal food, where the use of extracts based on organic solvents, like methanol, are not suitable

Polymeric Inclusion Membranes Based on Ionic Liquids for Selective Separation of Metal Ions

In this work, poly(vinyl chloride)-based polymeric ionic liquid inclusion membranes were used in the selective separation of Fe(III), Zn(II), Cd(II), and Cu(II) from hydrochloride aqueous solutions. The ionic liquids under study were 1-octyl-3-methylimidazolium hexafluorophosphate, [omim+][PF6−] and methyl trioctyl ammonium chloride, [MTOA+][Cl−]. For this purpose, stability studies of different IL/base polymer compositions against aqueous phases were carried out. Among all polymer inclusion membranes studied, [omim+][PF6−]/PVC membranes at a ratio of 30/70 and [MTOA+][Cl−]/PVC membranes at a ratio of 70/30 were able to retain up to 82% and 48% of the weight of the initial ionic liquid, respectively, after being exposed to a solution of metal ions in 1 M HCl for 2048 h (85 days). It was found that polymer inclusion membranes based on the ionic liquid methyl trioctyl ammonium chloride allowed the selective separation of Zn(II)/Cu(II) and Zn(II)/Fe(III) mixtures with separation factors of 1996, 606 and, to a lesser extent but also satisfactorily, Cd(II)/Cu(II) mixtures, with a separation factor of 112. Therefore, selecting the appropriate ionic liquid/base polymer mixture makes it possible to create polymeric inclusion membranes capable of selectively separating target metal ions

Effective high-energy ball milling in air of Fe65Co35 alloys

Fe65Co35 alloys are technologically relevant, especially in magnetic storage and composite permanent magnets, due to the fact that they present higher saturation magnetization per volume than any other material. Out of the various approaches undertaken for its production, mechanical ball milling remains the most common and efficient method, especially considering the large industrial scale of the applications. With the development of cost-efficient processing in mind, the influence of performing the synthesis of the FeCo alloys in air instead of the standard argon atmosphere is studied. The structural and magnetic characterization, along with the study of the oxygen content of the samples, proves that synthesizing FeCo alloys in air produce materials with nearly identical magnetic performance as their argon-milled counterpart, with the oxidation extent of the materials consisting almost exclusively of the oxide passivating layer located at the surface. In addition, no aging effect was observed in the saturation magnetization up to 6 months. It is concluded that the use of argon atmospheres, desiccators and/or glove boxes may be entirely removed from the process without affecting the magnetic properties.The authors would like to thank financial support from the European Commission through the Project NANOPYME FP7-NMP-2012-SMALL-6 NANOPYME No. 310516, and from the Spanish Ministerio de Economía y Competitividad through the Juan de la Cierva program and through Project No. MAT 2010-21088-C03-01

Imán permanente, procedimiento de obtención y usos

Imán permanente, procedimiento de obtención y usos. La presente invención se refiere a un imán permanente que comprende partículas magnéticas duras y una estructura magnética blanda con relación de aspecto mayor o igual a 3 y con estructura magnética de monodominio. Además, la presente invención se refiere al procedimiento de obtención de dicho imán y al uso de dicho imán como parte de un generador o un vehículo automóvil. La presente invención se encuadra en el sector de los materiales magnéticos y sus aplicaciones industriales.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad Complutense de Madrid, General Numerics Research Lab E.VA1 Solicitud de patente con informe sobre el estado de la técnic

Informe anual hacia la sociedad de la información y el conocimiento: Informe 2007

El presente documento es el segundo informe que con el título “Hacia la Sociedad de la Información y el Conocimiento, 2007”, elabora el Programa de la Sociedad de la Información y el Conocimiento (PROSIC) de la Universidad deCosta Rica. Su propósito es presentar anualmente una visión actualizada y sistematizada de los aspectos mas relevantes de las tecnologías de la información y la comunicación (TIC) en Costa Rica, así como examinar la forma en que estas influyen en aspectos específicos de la vida nacional en sus distintas dimensiones: jurídica, institucional, económica, social, política y cultural. El Informe incluye diez capítulos y un anexo estadístico.UCR::Rectoría::Programa Sociedad de la Información y el Conocimiento (PROSIC

FeCo nanowire−strontium ferrite powder composites for permanent magnets with high-energy products

Due to the issues associated with rare-earth elements, there arises a strong need for magnets with properties between those of ferrites and rare-earth magnets that could substitute the latter in selected applications. Here, we produce a high remanent magnetization composite bonded magnet by mixing FeCo nanowire powders with hexaferrite particles. In the first step, metallic nanowires with diameters between 30 and 100 nm and length of at least 2 μm are fabricated by electrodeposition. The oriented as-synthesized nanowires show remanence ratios above 0.76 and coercivities above 199 kA/m and resist core oxidation up to 300 °C due to the existence of a >8 nm thin oxide passivating shell. In the second step, a composite powder is fabricated by mixing the nanowires with hexaferrite particles. After the optimal nanowire diameter and composite composition are selected, a bonded magnet is produced. The resulting magnet presents a 20% increase in remanence and an enhancement of the energy product of 48% with respect to a pure hexaferrite (strontium ferrite) magnet. These results put nanowire−ferrite composites at the forefront as candidate materials for alternative magnets for substitution of rare earths in applications that operate with moderate magnet performance.We would like to thank Dr. Vić tor Fuertes for his advice on the processing of the bonded magnets. This work is supported by the Spanish Ministerio de Economía y Competitividad y Ministerio de Ciencia e Innovación (Project Nos. MAT2017- 86450-C4-1-R, MAT2015-64110-C2-1-P, MAT2015-64110- C2-2-P, MAT2017-87072-C4-2-P, RTI2018-095303-A-C52, and FIS2017-82415-R) and by the European Commission through Project H2020 (No. 720853; AMPHIBIAN). C.G.-M. acknowledges financial support from MICINN through the “Juan de la Cierva” Program (FJC2018-035532-I). A.Q. acknowledges financial support from MICINN through the “Ramón y Cajal” Program (RYC-2017-23320). The work also is funded by the Regional Government of Madrid (Project S2018/ NMT-4321; NANOMAGCOST)