Closed-form equation for natural frequencies of beams under full range of axial loads modeled with a spring-mass system

A new simple closed-form equation that accurately predicts the effect of an arbitrarily large constant axial load, residual stress or temperature shift on the natural frequencies of an uniform single-span beam, with various end conditions, is presented. Its accuracy and applicability range are studied by comparing its predictions with numerical simulations and with the approximate Galef’s and Bokaian’s formulas. The new equation may be understood as a refinement or extension of these two approximate formulas. Significant accuracy and applicability range improvements are achieved, especially near the buckling point and for large and moderate axial load. The new closed-form equation is applicable in the full range of axial load, i.e., from the buckling load to the tensioned-string limit. It also models well the beam-to-string transition region for the eight boundary conditions studied. It works remarkably well in the free-free and sliding-free cases, where it is a near-exact solution. In addition, it yields the natural frequencies of a 1-D spring-mass system that may be used to model tensioned beams, and potentially, more complex systems.Peer ReviewedPostprint (published version

Laboratorios virtuales de redes: sí, inténtelo en casa

Las asignaturas de redes y servicios distribuidos han adquirido un papel destacado en los nuevos títulos de grado en Informática. Habitualmente, las actividades prácticas de diseño y configuración de redes requieren de costosas infraestructuras de laboratorio, con recursos compartidos que limitan el número de alumnos que pueden simultanear su manejo. No obstante, las nuevas posibilidades que ofrece la virtualización permiten explorar alternativas realistas con routers y switches virtuales que se pueden manejar en entornos de laboratorio con poca infraestructura. Este artículo repasa las posibilidades existentes para la docencia de laboratorios de redes y argumenta las soluciones adoptadas en la Universidad de Málaga con énfasis en actividades de carácter no presencialSUMMARY: Computer Networks and Distributed Services have a relevant role in the Degree on Informatics curricula. Usually, the practical tasks regarding the design and configuration of network topologies require expensive infrastructures for laboratories with shared resources (routers, switches) which limit the number of students that can manage them simultaneously. However, new trends and possibilities in virtualization allow professors to explore new ways to develop and practice with complex network topologies in a cheaper way. This paper reviews the existing approaches in virtualization to teach subjects focused on networking, and argues what are the solutions planned at the University of Málaga, with focus on on-line and distance learning activities.Peer Reviewe

El contexto social de la producción y circulación de cerámicas y elementos de adorno en el Neolítico Antiguo del Sur de Córdoba

En esta contribución discutiremos la pertinencia de un modelo social basado en redes supralocales con reciprocidad equilibrada para explicar la fenomenología de los atributos técnicos, arqueométricos y de estilo decorativo de las producciones alfareras y de la materia prima soporte de los denominados brazaletes a partir de la producción masiva de estos últimos en un lugar especializado que parece no atender sólo a la función utilitaria-simbólica del adorno en la vida social del seno de estos grupos locales, sino que trascendiéndola, responde a otros usos sociales intergrupales ligados al intercambio

Curvature of BEOL cantilevers in CMOS-MEMS processes

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents the curvature characterization results of released back-end-of-line 5 µm-wide cantilevers for two different 0.18-µm 1P6M complementary metal-oxide semiconductor microelectromechanical systems processes. Results from different runs and lots from each foundry are presented. The methodology and accuracy of the characterization approach, based on optical measurements of test cantilever curvature, are also discussed. Special emphasis is given to the curvature average and variability as a function of the number of stacked layers. Analythical equations for modeling the bending behavior of stacked cantilevers as a function of the tungsten (W) vias that join the metal layers are presented. In addition, the effect of various post-processing conditions and design techniques on the curvature of both single and stacked cantilevers is analyzed. In particular, surpassing certain time-dependent temperature stress conditions after release lead to curvature shifts larger than one order of magnitude. Also, the W via design was found to strongly affect the curvature of the test cantilevers.Peer ReviewedPostprint (author's final draft

Elementos de una organización educativa inclusiva para la respuesta a alumnado con necesidades educativas especiales de educación secundaria en Italia. La situación en un instituto profesional

El presente trabajo aborda la experiencia de la inclusión escolar en su dimensión organizacional en la etapa de educación secundaria obligatoria en el contexto italiano. Aun siendo un tema recurrente, no deja de ser un tema que en la práctica preocupa con intensidad al profesorado, a las familias y a los gestores educativos, por ello se ha tenido como objetivo fundamental analizar la situación real de la inclusión vivida y percibida por los actores sobre la organización de su institución. Metodológicamente se ha afrontado desde un estudio de caso de un instituto de secundaria de relevancia con respecto a la problemática, por su tamaño, por el impacto del problema en su seno y por su ubicación en una zona de sur de Italia con especial penetración social y escolar de la problemática de la diversidad en los centros escolares. Nos hemos encontrado con unos resultados que denotan la gran fractura que existe entre la evolución del discurso y su proyección real. Mientras la inicial integración ha quedado subsumida desde hace ya tiempo, en un paradigma más universal como es el de la inclusión, la realidad arroja datos que nos retrotraen a momentos menos evolucionados de este paradigma. La inclusión es más teórica que real, alcanza el plano de la planificación y del diseño, pero menos el de la práctica docente, con déficit notables en coordinación, en trabajo de equipo específico, y con una demanda de formación reiterada

La educación emprendedora en Andalucía. Un enfoque integrado

When evaluating the relevance of actions within the area of entrepreneurship education, the quite remarkable national and regional differences regarding entrepreneurial culture, entrepreneurial potential and, of course, the business structure, have to be taken into account. Based on these differences, there is a need to specifically design entrepreneurial education policies which take into account the strengths and weaknesses of the business structure of each region. This paper aims to identify the structural characteristics of the Andalusian entrepreneurial model in comparison with that of other Spanish regions. To do this, a database of over 1000 companies have been used coming from the Research Project (Ref. P09- SEJ -4857) carried out by the "SMEs and economic development" research group (SEJ -128) of the University of Seville. This information will also be complemented with regional reports from the GEM project. From these two data sources, an eminently qualitative profile of the structural weaknesses of existing businesses and their entrepreneurs in Andalusia will be established. From this analysis of regional needs, we will raise our differential proposition for an embedded education towards entrepreneurship. It will identify and include the content and pedagogical techniques necessary to overcome these weaknesses of the regional business community.Al evaluar la pertinencia de las acciones en el ámbito de la educación empresarial, las notables diferencias nacionales y regionales con respecto a la cultura emprendedora, el potencial empresarial y, por supuesto, la estructura empresarial, han de ser tenidos en cuenta. Sobre la base de estas diferencias, hay una necesidad de diseñar políticas específicas de educación emprendedora que tengan en cuenta las fortalezas y debilidades de la estructura empresarial de cada región. Este trabajo tiene como objetivo identificar las características estructurales del modelo empresarial andaluz en comparación con el de otras regiones españolas. Para ello, se ha usado una base de datos de más de 1.000 empresas procedente del Proyecto de Investigación (Ref. P09- SEJ -4857) llevado a cabo por el grupo de investigación "PYME y desarrollo económico” (SEJ -128) de la Universidad de Sevilla. Esta información también se complementará con los informes regionales del proyecto GEM. A partir de estas dos fuentes de datos, se establecerá un perfil eminentemente cualitativo de las debilidades estructurales de las empresas existentes en Andalucía y de sus empresarios. A partir de este análisis de las necesidades regionales, vamos a plantear nuestra propuesta diferencial para una educación emprendedora integrada. Se identificará e incluirá el contenido y las técnicas pedagógicas necesarias para superar estas debilidades de la comunidad empresarial regional

Combining dimensional analysis with model based systems engineering

The model based systems engineering (MBSE) approach describes a system using consistent views to provide a holistic model as complete as possible. MBSE methodologies end with the physical architecture of the system, but a physical model is clearly incomplete without the study of its associated physical laws and phenomena related to the whole system or its parts. However, the computational demands could be excessive even for modest projects. Dimensional analysis (DA) is common in fluid dynamics and chemical engineering, but its application to systems engineering is still limited. We describe an engineering methodological process, which incorporates DA as a powerful tool to understand the physical constraints of the system without the burden of complex analytical or numerical calculations. A detailed example describing a microantenna is presented showing the benefits of this approach. The selected example describes a problem rarely covered in modern expositions of DA in order to show the wide benefit of these techniques. The information provided by this analysis is very useful to select the best physically realizable architectures, testing design, and conduct trade-off studies. The complexity of modern systems and systems of systems demands new testing procedures in order to comply with increasingly demanding requirements and regulations. This can be accomplished through research in new DA methods. Finally, this article serves as a fairly comprehensive guide to the use of DA in the context of MBSE, detailing its strengths, limitations, and controversial issues

3D-form metrology of arbitrary optical surfaces by absorption in fluids

We present an imaging technique for the 3D-form metrology of optical surfaces. It is based on the optical absorption in fluids situated between the surface and a reference. An improved setup with a bi-chromatic light source is fundamental to obtain reliable topographic maps. It is able to measure any surface finish (rough or polished), form and slope and independently of scale. We present results focused on flat and spherical optical surfaces, arrays of lenses and with different surface finish (rough-polished). We achieve form accuracies from several nanometers to sub-lambda for sag departures from tens to hundred of microns. Therefore, it seems suitable for the quality control in the production of precision aspheric, freeform lenses and other complex shapes on transparent substrates, independently of the surface finish

Optimized profile planar UWB monopole antenna for optimal adaptation

This work deals with the possibility of making a completely blind optimization of th profile of a planar monopole antenna in order to satisfy previously defined demands, in this case minimal return losses for an UWB system. Previous results in this topic were already discussed in [1]. In that work, optimization of the profile of the antenna was not completely blind due to the high computational effort needed to obtain results, which can tirn to be a complete failure. Hence, to speed up the method, the global optimization was performed using a less accurate but quicker analysis and then refining the solution with a local optimization using a very accurate analysis