Study of resonant modes in a 700 nm pitch macroporous silicon photonic crystal

In this study the modes produced by a defect inserted in a macroporous silicon (MP) photonic crystal (PC) have been studied theoretical and experimentally. In particular, the transmitted and reflected spectra have been analyzed for variations in the defect’s length and width. The performed simulations show that the resonant frequency is more easily adjusted for the fabricated samples by length tuning rather than width. The optimum resonance peak results when centered in the PC bandgap. The changes in the defect geometry result in small variations of the optical response of the PC. The resonance frequency is most sensitive to length variations, while the mode linewidth shows greater change with the defect width variation. Several MPS photonic crystals were fabricated by the electrochemical etching (EE) process with optical response in the range of 5.8 µm to 6.5 µm. Results of the characterization are in good agreement with simulations. Further samples were fabricated consisting of ordered modulated pores with a pitch of 700 nm. This allowed to reduce the vertical periodicity and therefore to have the optical response in the range of 4.4 µm to 4.8 µm. To our knowledge, modes working in this range of wavelengths have not been previously reported in 3-d MPS structures. Experimental results match with simulations, showing a linear relationship between the defect’s length and working frequency inside the bandgap. We demonstrate the possibility of tailoring the resonance peak in both ranges of wavelengths, where the principal absorption lines of different gases in the mid infrared are placed. This makes these structures very promising for their application to compact gas sensors.Postprint (author's final draft

Experimental Damage Identification in Masonry Structures by OMA

This paper presents a study carried out in different types of masonry structures to identify existing damage through dynamic identification techniques using operational modal analysis. A cross vault, a masonry wall and a simple clay brick construction have been analyzed. The three cases have been tested on a full scale in the laboratory. The cross vault has been subjected to a settlement of one of its supports, the damage has occurred and then it has been repaired by using Textile Reinforced Mortars (TRM). In the case of the wall and the simple construction, the damage has been generalized by means of horizontal loads simulating a seismic action by a cyclic incremental load, after the generation of the damage, it has been repaired using TRM. In all cases, a dynamic identification has been carried out prior to the generation of the damage, after the generation of the damage and later after its repair, finally after a new process of damage the structural health changes have been monitored. In the four phases, an identification of the dynamic characteristics of the structures has been carried out, both main frequencies and damping factor associated with each mode shape. Regarding operational modal analysis, the first vibration modes have been identified. Singular Value Plot have been obtained through the EFDD technique. In general terms, the results of the investigation showed that the effect of cracking generated by both horizontal cyclic loads and vertical displacements located in one of the supports generated a decrease in the vibration frequencies and an increase in the structural damping factors for the different vibration modes. On the other hand, in relation to the effect of the reinforcement techniques employed, the results showed the feasibility of recovering or even slightly increasing the stiffness of the original damaged structure. However, the results for the strengthened structures also showed that the intervention on the damaged structure tended to reduce the structural damping factors with respect to the unreinforced structure. In addition, it was also observed that after the tests the reinforced and newly damaged structures showed dynamic characteristics very similar to the unreinforced damaged structures.The authors want to acknowledge Spanish Ministry of Universities for the funding provided through Projects RTI2018-101148-B-100 and BIA2015-69952-R, and also the Grupo Mapei and the Grupo Puma for their invaluable assistance

Dynamic behavior of masonry chimney with different reinforcement schemes

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.This paper presents a structural analysis of a masonry chimney built in the 1950’s, which is currently being catalogued as local interest heritage. These structures exhibit insufficient tensile strength to resist the seismic action because the masonry is not reinforced. For this reason, the aim of this work is to analyze different structural reinforcement schemes so the chimney is capable of withstanding seismic actions. Ten numerical models, for nine reinforcement configurations, have been defined using Ansys software. A glass fiber reinforced cement composite was always used as reinforcement. For each model, a modal analysis and time history analyses were made. Five different synthetic accelerograms were used for the structural analysis, according to NCSE02 Spanish standard. The final reinforcement, capable of resisting the seismic action, consisted of a helicoid wrap and eight longitudinal stripes along the shaft, and the inner and outer reinforcement of all masonry walls of the base

In-plane shear cyclic behavior of windowed masonry walls reinforced with textile reinforced mortars

The current experimental study is focused on the mechanical performance of masonry walls under in-plane cyclic shear forces. All specimens were fabricated with a central window, in which the geometry considered the recommendations of the Spanish structural seismic design code. Windows represent a weak area in the masonry structure, in which there are stress concentrations responsible for crack initiation. In order to improve the mechanical strength and ductility, a reinforcement with a Textile Reinforced Mortar (TRM) was used on both sides of the wall. The performance of the unreinforced and reinforced masonry has been discussed in terms of strength and ductility gain, stiffness degradation and energy dissipation capacity. The experimental tests comprised an initial vertical preload, and shear cycles with increasing amplitude. All tests were monitored by means of traditional displacement transducers, and digital image correlation. The analysis of the images showed the time evolution of the overall crack distribution. The TRM effect could be observed as an increase of the mechanical strength (maximum shear from 120 kN to more than 300 kN), higher displacements (drift from 9 to 35 mm), and more energy dissipation (the cumulative energy loss from 2.7 to 12.7 kN·m). In addition, the TRM reinforcements were capable of controlling the crack initiation and growth. The widespread crack along mortar joints observed in the unreinforced masonry became localized cracks (from the window’s corners mainly), in which crack growth direction was not determined by masonry joints.The authors would like to acknowledge Mapei Spain S.A. for the materials supplied in this research. This research was funded by Spanish Ministry of Economy and Competitiveness, grant number BIA2015-69952-R and Spanish Ministry of Science, Innovation and Universities, grant number RTI2018-101148-B-I00

Spatial patterns of bacteria show that members of higher taxa share ecological characteristics

Affiche, résuméWhether bacteria display spatial patterns of distribution and at which level of taxonomic organization such patterns can be observed are central questions in microbial ecology. Here we investigated how the total and relative abundances of eight bacterial taxa at the phylum or class level were spatially distributed in a pasture by using quantitative PCR and geostatistical modelling. The distributions of the relative abundance of most taxa varied by a factor of 2.520136.5 and displayed strong spatial patterns at the field scale. These spatial patterns were taxon-specific and correlated to soil properties, which indicates that members of a bacterial clade defined at high taxonomical levels shared specific ecological traits in the pasture. Ecologically meaningful assemblages of bacteria at the phylum or class level in the environment provides evidence that deep branching patterns of the 16S rRNA bacterial tree are actually mirrored in nature

Seismic behavior of 1960's RC buildings exposed to marine environment

Steel rebars corrosion is one of the most important problems of reinforced concrete (RC) structures. The mechanical performance loss of RC elements because of steel corrosion can be aggravated under horizontal loads (e.g. wind pressure or seismic actions). This paper presents a methodology for the study of the seismic behavior of a residential typology of the Mediterranean coast, which was widely spread during the 1960's. These RC frame structures are usually 10 to 15 stories high, located very close to the coast and are exempt buildings, which made them specially exposed to chloride corrosion. Besides, there are some design conditions that should be taken into account: (i) these structures were designed only under gravity loads, especially seismic actions were not considered. (ii) The raw materials had lower quality than those considered in current design codes, e.g. structural concrete strength was around 15 MPa, and made with natural beach sand as fine aggregates (hence including chlorides into the concrete mass). Therefore, two important aspects converge in these buildings, fifty years of marine exposure (i.e. degradation by corrosion) and the omission of the seismic loads in the original design, making them especially vulnerable to earthquakes (in an area with a moderate-high seismicity). Hence, a methodology for the seismic analysis of the corroded structure is proposed, in order to determine the structural safety factor of this type of structures, and evaluate the effectiveness of a retrofitting if necessary

Transmission and thermal emission in the NO2 and CO absorption lines using macroporous silicon photonic crystals with 700 Nm pitch

Postprint (author's final draft

Estudio numérico para consolidación mediante fijación de fracturas verticales en cuello de fémur

Las fracturas del cuello femoral (FNF) son un problema creciente en ortopedia y traumatología, afectando a personas de todas las edades y géneros. El sistema de clasificación Pauwels divide estas fracturas en tres tipos según la verticalidad de ella, siendo la de tipo III (ángulo >50º) las más difíciles de tratar. La elección del tratamiento o sistema de fijación, sigue siendo un desafío debido a la falta de guías estandarizadas. Este estudio se enfoca en comparar tres tipologías de sistemas de fijación interna, CS y XCS tipo 1 y tipo 2, a partir de 24 modelos numéricos, evaluando su efecto en la rigidez del sistema, así como de las tensiones tanto en el sistema óseo como en el propio sistema de fijación. El reducido número de investigaciones en esta línea de trabajo resalta la importancia de esta investigación para mejorar el conocimiento, el tratamiento de las FNF y la calidad de vida de los pacientes afectados

Experimental analysis of the loss of bond between rebars and concrete exposed to high temperatures

En el conjunto de materiales de construcción habituales en la edificación y las obras de ingeniería, el hormigón destaca entre otras razones por su excelente comportamiento frente a las altas temperaturas y la exposición al fuego. El presente estudio se centra en la adherencia residual entre el hormigón y las barras de acero corrugado soldable tras exponer probetas a altas temperaturas y enfriarlas hasta temperatura ambiente por convección natural. El estudio incluye hormigones de resistencia convencional, hormigones de alta resistencia y hormigones reforzados con fibras de polipropileno y fibras de acero. La adherencia hormigón-acero se ha medido mediante el conocido ensayo de pull-out. La campaña experimental también ha incluido la resistencia a compresión y la resistencia a tracción indirecta. Parte de las probetas se han ensayado a 28 días de edad a temperatura ambiente. A 60 días de edad se han repetido los ensayos a temperatura ambiente y se han realizado esos mismos ensayos en probetas calentadas en un horno industrial hasta tres rangos de temperatura: 450°C, 650°C y 825°C. Previo al proceso de calentamiento han sido sometidas durante 3 horas a un escalón de secado a 120°C. Mediante la metodología propuesta ha sido posible caracterizar la evolución de la pérdida de adherencia residual entre el acero y el hormigón conforme se exponen los especímenes a temperaturas más elevadas. La adición de fibras no tiene una influencia clara en la adherencia a temperatura ambiente. Sin embargo, sí se ha conseguido determinar una mejora sustancial de la adherencia residual en los hormigones, reforzados con fibras de acero sometidos a altas temperaturas.Within the context of the most usual construction materials for building and civil infrastructures, concrete stands out because of its excellent behaviour when exposed to high temperatures and fire condition. The present study focuses on the residual bond strength between concrete and steel rebars after exposure to elevated temperatures and natural cooling to room temperature. Normal strength and high strength concretes have been tested, as well as polypropylene and steel fibre reinforced concretes. The bond strength has been measured using the pull-out test. Compressive and tensile strength have also been determined. Some specimens have been tested at an age of 28 days and at room temperature. At 60 days the tests have been repeated at room temperature and after heating up to three temperature ranges: 450°C, 650°C and 825°C. Before each of the three heating phases, the specimens were pre-heated during 3 hours at 120 °C. After these experiments it has been possible to assess the loss of steel-concrete bonding for higher temperatures. The addition of fibres has no clear influence on the bonding at ambient condition. However, an improvement on the residual bonding strength has been observed for steel fibre reinforced concrete under high temperatures

Aspectos económicos y modelos de negocio del software libre

218 p. : il. ; 30 cm.Libro ElectrónicoLa asignatura de Aspectos económicos y modelos de negocio del software libre tiene el objetivo de proporcionar los conocimientos necesarios para comprender y poner en práctica la economía del software libre mediante el estudio y el análisis de los aspectos económicos y de los modelos de negocio relacionados, así como de las oportunidades que ofrece este nuevo mercado.El libro Aspectos económicos y modelos de negocio del software libre tiene el objetivo de proporcionar los conocimientos necesarios para comprender y poner en práctica la economía del software libre median- te el estudio y el análisis de los aspectos económicos y de los modelos de negocio relacionados, así como de las oportunidades que ofrece este nuevo mercado. En nuestra sociedad, las industrias de las tecnologías de la información y del conocimiento (TIC), es decir, las telecomunicaciones, la electrónica (de producción y de consumo) y la informática han cobrado una importancia desconocida tiempo atrás. Se ha producido un ritmo extraordinario de innovación en estas industrias, acompañado de un proceso de convergencia entre ellas, manipulando, transmitiendo y reproduciendo la información con procedimientos comunes: las tecnologías digitales. Pero, más allá de los cambios que se han producido en las industrias directamente relacionadas con las TIC, tienen mucha más importancia los cambios y mejoras que han influido en otras actividades económicas, especialmente las más tradicionales, donde la manera de proceder ha vivido una remodelación en profundidad. Las consecuencias en el tejido económico han propiciado la apertura de nuevas áreas de negocio que responden a nuevas demandas del mercado, inéditas tiempo atrás. Ahora bien, ninguna ley económica ha cambiado y ninguno de los fenómenos económicos relacionados con las TIC son cualitativamente nuevos. Si acaso, lo que ha cambiado es la importancia relativa de determinados efectos económicos en nuestra sociedad, como por ejemplo las políticas de propiedad intelectual o de compatibilidad de los productos. Si nos centramos más concretamente en los efectos económicos relevantes en la industria del software, llegaremos a una conclusión parecida.Módulo didáctico 1 Nociones básicas de economía Lluís Bru Martínez 1. La creación de valor 2. Características económicas de la industria del software Módulo didáctico 2 El mercado del software Lluís Bru Martínez 1. Negocios con características similares al software libre 2. ¿Quiénes necesitan software? Módulo didáctico 3 Software como negocio Irene Fernández Monsalve 1. Posibilidades de negocio en torno al software 2. Empresas dominantes en el sector 3. Marketing en la empresa: ¿A quién vender? 4. Función del producto: ¿Qué vender? Módulo didáctico 4 Modelos de negocio con software libre Irene Fernández Monsalve 1. Caracterizando modelos de negocio con software libre 2. Clasificaciones según distintos autores 3. Modelos de negocio con software libre Módulo didáctico 5 Desarrollar software libre en una empresa Amadeu Albós Raya 1. La producción de software libre 2. La comunidad de usuarios 3. Caso de estudio Módulo didáctico 6 Estrategias del software libre como negocio Amadeu Albós Raya 1. La competitividad del software libre 2. La perspectiva del cliente 3. La estrategia empresarial Módulo didáctico 7 El software libre, ¿un nuevo modelo económico? Amadeu Albós Raya 1. Las bases del modelo 2. Las características del modelo del software libre 3. La validez y la viabilidad del modelo del software libr