B.I.E.M. y estudio de singularidades en problemas de potencial

El objeto del presente artículo es el estudio de singularidades en problemas de Potencial mediante el uso del Método de las Ecuaciones Integrales sobre el contorno del dominio en estudio. Frente a soluciones basadas en la mejora de la discretización, análisis asintótico o introducción de funciones de forma que representen mejor la evolución de la función, una nueva hipótesis es presentada: el término responsable de la singularidad es incluido en la integral sobre el contorno de la función auxiliar. Los resultados obtenidos mejoran los de soluciones anteriores simplificando también el tiempo de cálculo = The subject of this paper is the modelling of singularities in potential problems, using the Boundary Integral Equation Method. As a logical alternative to classical methods (discretization refinement, asymptotic analysis, high order interpolatory functions) a new hypothesis is presented: the singularity responsible term is included in the interpolatory shape function. As shown by several exemples results are splendid and computer time radically shortened.

Simulación numérica por el Método de los Elementos de Contorno. Utilización de elementos isoparamétricos parabólicos

Se presenta en esta comunicación el tratamiento de problemas de potencial en sistemas bidimensionales, haciendo uso de la discretización de su contorno o frontera mediante elementos parabólicos tanto en geometría como en las variables de campo. Se estudian las ventajas frente al uso de elementos isoparamétricos lineales dentro de la teoría del potencial. Se presenta también un estudio sobre las zonas singulares a que dan lugar los elementos parabólicos degenerados = This paper presents a B.I.E.M. for potential theory, using in the discretization a completely isoparametric parabolic formulation; that is, the field variable, its first derivative and the boundary domain are interpolated using second orden piecewise polinomic. Several results are presented and comparison is mode with other simpler formulations. Also treated is the posibility of modelling singular behavior by moving the midside mode of selected elements.

Simulación de registros sísmicos a partir de espectros de diseño

La simulación de registros sísmicos, compatibles con espectros medios de diseño, se ha convertido en una necesidad en los últimos años, debido principalmente a su exigencia en la norma de regulación del cálculo de centrales nucleares. En este trabajo se presentan distintas posibilidades de realización de esta simulación, así como una comparación entre ellas, apareciendo como una alternativa efectiva a los métodos clásicos la utilización del contenido de fase de los seismos reales. Mediante ello se establece un procedimiento que elimina la arbitrariedad que supone el uso de una función envolvente para definir la característica no estacionaria del registro. Los distintos métodos son descritos detalladamente, así como la influencia de los diferentes parámetros que intervienen en cada uno de ellos. Por último se presentan algunos ejemplos numéricos = The simulation of spectrum-compatible earthquake time histories, has been a need since the beginning of the development of earthquake engineering for complicated structures. More than the safety of the main structure, the analysis of the equipment (piping, rackes, etc.) can be assesed only on the basis of time-histories of the floor in which they are contained. This paper presents several alternatives to the generation of sinthetic time histories and the use of the distribution of the differences among the phase-angles is demonstrated to be a useful tool to simulate the nonstationarity of the process. Thorugh the paper an extensive use is made of the F.F.T. algorithm.

E.D.A.R. Renedo de Piélagos (Cantabria)

Las obras definidas en este proyecto están integradas dentro del “Plan Director de Saneamiento y Depuración de Aguas Residuales de Cantabria”, que contempla la actuación en materia de saneamiento por determinadas zonas o cuencas hidrográficas, de acuerdo con la Directiva 91/271/CEE. La Estación Depuradora de Aguas Residuales (E.D.A.R) de Renedo de Piélagos, perteneciente al “Saneamiento de la Cuenca Media del Pas-Pisueña” tiene por objeto el tratamiento de los vertidos de aguas residuales de los municipios de Santa María de Cayón, Castañeda, Puente Viesgo y Piélagos de modo que se garantice una adecuada calidad de las aguas de los ríos Pisueña y Pas. El objeto del presente proyecto es la completa definición del conjunto de obras necesarias para el correcto funcionamiento del tratamiento de aguas residuales procedentes de los municipios de la cuenca media del Pas-Pisueña. De acuerdo con los objetivos generales perseguidos por las actuaciones a realizar, se pretende dotar a la zona de una Estación Depuradora de Aguas Residuales en Renedo de Piélagos necesaria para asegurar el correcto funcionamiento de la red. De esta forma se intenta evitar los vertidos directos a los ríos y arroyos de la zona, y de este modo, garantizar la calidad ambiental del medio receptor, que una vez finalizadas las actuaciones será el río Pas. El ámbito de actuación de este proyecto abarca los términos municipales de Puente Viesgo, Castañeda y Piélagos, aunque el colector interceptor principal, que dará servicio a la E.D.A.R. de Renedo de Piélagos, se diseña con capacidad suficiente para recoger una futura incorporación de los caudales de aguas residuales del municipio de Sta. María de Cayón.

Método de los Elementos de Contorno en algunos problemas de interacción suelo-estructura

Los problemas del comportamiento sismico de estructuras masivas de gran responsabilidad y edificios de gran altura asi como el clásico problema del cimiento de las maquinas vibrantes, hacen que el estudio de la interacci6n suelo- estructura adquiera una gran actualidad. Estos problemas, que implican formas y propiedades complicadas, suponen siempre la necesidad de utilizar un modelo numerico del medio considerado. Aqui se emplea el metodo de los elementos de contorno que dadas sus caracteristicas resulta una alternativa muy sugestiva para modelar el suelo y que hace posible el estudio de problemas tridimensionales a un precio razonable. Se introduce un tipo de elementos para problenas bidimensionales , que incluye una singularidad de tipo logaritmico en uno de sus extremos.Se muestran distribuciones de tensiones obtenidas con este tipo de elementos.

A new UTD for the electromagnetic plane wave scattering by a canonical circular cylinder with an impedance boundary condition

A UTD solution is developed for describing the scattering by a circular cylinder with an impedance boundary condition (IBC), when it is illuminated by an obliquely incident electromagnetic (EM) plane wave. The solution to this canonical problem will be crucial for the construction of a more general UTD solution valid for an arbitrary smooth convex surface with an IBC, when it is illuminated by an arbitrary EM ray optical field. The canonical solution is uniformly valid across the surface shadow boundary that is tangent to the surface at grazing incidence. This canonical solution contains cross polarized terms in the scattered fields, which arise from a coupling of the TEz and TMz waves at the impedance boundary on the cylinder. Here, z is the cylinder axis. Numerical results show very good accuracy for the simpler and efficient UTD solution, when compared to exact but very slowly convergent eigenfunction solution.

Interaction between a laser beam and semiconductor nanowires: application to the raman spectrum of Si nanowires

One presents in this work the study of the interaction between a focused laser beam and Si nanowires (NWs). The NWs heating induced by the laser beam is studied by solving the heat transfer equation by finite element methods (FEM). This analysis permits to establish the temperature distribution inside the NW when it is excited by the laser beam. The overheating is dependent on the dimensions of the NW, both the diameter and the length. When performing optical characterisation of NWs using focused laser beams, one has to consider the temperature increase introduced by the laser beam. An important issue concerns the fact that the NW's diameter has subwavelength dimensions, and is also smaller than the focused laser beam. The analysis of the thermal behaviour of the NWs under the excitation with the laser beam permits the interpretation of the Raman spectrum of Si NWs. It is demonstrated that the temperature increase induced by the laser beam plays a major role in shaping the Raman spectrum of Si NWs.

Assessing the impact of adaptive accessibility on the optimal transport policy implementation by using an integrated land-use/transport model for Madrid

Accessibility is an essential concept widely used to evaluate the impact of land-use and transport strategies in transport and urban planning. Accessibility is typically evaluated by using a transport model or a land-use model independently or successively without a feedback loop, thus neglecting the interaction effects between the two systems and the induced competition effects among opportunities due to accessibility improvements. More than a mere methodological curiosity, failure to account for land- use/transport interactions and the competition effect may result in large underestimation of the policy effects. With the recent development of land-use and transport interaction (LUTI) models, there is a growing interest in using these models to adequately measure accessibility and evaluate its impact. The current study joins this research stream by embedding an accessibility measure in a LUTI model with two main aims. The first aim is to account for adaptive accessibility, namely the adjustment of the potential accessibility due to the effect of competition among opportunities (e.g., workplaces) as a result of improved accessibility. LUTI models are particularly suitable for assessing adaptive accessibility because the competition factor is a function of the number of jobs, which is related to land-use attractiveness and the number of workers which is related, among other factors, to the transport demand. The second aim is to identify the optimal implementation scenario of policy measures on the basis of the potential and adaptive accessibility and analyse the results in terms of social welfare and accessibility. The metropolitan area of Madrid is used as a case-study and two transport policy instruments, namely a cordon toll and bus frequency increase, have been chosen for the simulation study in order to present the usefulness of the approach to urban planners and policy makers. The MARS model (Metropolitan Activity Relocation Simulator) calibrated for Madrid was employed as the analysis tool. The impact of accessibility is embedded in the model through a social welfare function that includes not only costs and benefits to both road users and transport operators, but also costs and benefits for the government and society in general (external costs). An optimisation procedure is performed by the MARS model for maximizing the value of objective function in order to find the best (optimal) policy imp lementations intensity (i.e., price, frequency). Last, the two policy strategies are evaluated in terms of their accessibility. Results show that the accessibility with competition factor influences the optimal policy implementation level and also generates different results in terms of social welfare. In addition, mapping the difference between the potential and the adaptive accessibility indicators shows that the main changes occur in areas where there is a strong competition among land-use opportunities.

Plaster reinforcement with fibers by mineral wool obtained from the recycle of construction and demolition waste

The use of mineral wool is becoming more widespread due to increased acoustic and thermal demands of Spanish Technical Building Code. This increase affects both in rehabilitation and new construction projects. Therefore, waste generation of this type of insulating material is having more importance. The main objective of this research is to study the possibility of recycling fiber obtained from mineral wool of the C&DW as an alternative material to chopped glass fibers that are currently used as reinforcing elements in the prefabricated plaster. To achieve this objective, series are made of plaster E-35 additived with rock wool residue and glass wool residue at different rates of addition. These series are repeated by changing the additive by E fiberglass (length of 25mm) to make a comparative analysis with respect to the series additived with mineral wool waste. All the series are subjected to the test to determine Shore C surface hardness and mechanical testing to determine the compressive and flexural strength. From the results it can be concluded that: with rock wool residue, increases Shore C hardness up to 15% with respect to the glass fiber and 9% with respect to the glass wool, with a percentage of addition 2%. With rock wool residue, weight is decreased by 5% with respect to the glass fiber and 4% with respect to the glass wool waste, with an addition percentage of 4%. For an addition rate of 4%, results in the flexural strength test with fiberglass are 85% higher than those obtained with glass wool residue. However, for a percentage of 1% addition, the results obtained with glass wool residue are 35% higher than those obtained with fiberglass. For an addition rate of 3% results in the compressive strength test with fiberglass are 54% lower than those obtained with rock wool waste and 70% lower than those obtained with glass wool waste. Comparing the two mineral wools, it can be concluded that up to 3% of the addition, the glass wool series results obtained are 10% higher than those additived with rock wool. However, higher percentages of addition show that the results obtained with rock wool are 35% higher than those obtained with glass wool. The general conclusion is that the series additived with mineral wool from C&DW show better results in tests than the ones used nowadays as plaster reinforcement.

Modelo para evaluar el capital social en programas de cooperación para el desarrollo

Los programas de desarrollo regional promovidos por los gobiernos nacionales y las agencias multilaterales, como el Banco Mundial y el Banco Interamericano de Desarrollo (BID), se orientan a las políticas públicas de suministro de bienes públicos, ya sean servicios públicos o infraestructuras, a las regiones subdesarrolladas. Las evidencias apuntan que el éxito de estos programas depende en parte de externalidades, las cuales se relacionan con los cambios del tejido asociativo y los valores de los participantes de la comunidad. Estas externalidades se definen como el capital social. Cómo las externalidades no son directamente evaluadas en el impacto económico y social de los proyectos, pero su existencia es aceptada por los planificadores que reconocen la importancia de desarrollar el tejido de relaciones en la comunidad. Sin embargo este capital social no es medido. El objeto de esta tesis es investigar y proponer procesos de medida y evaluación del capital social de un proyecto, y relacionarlos con las actividades del mismo en un territorio y proyecto dado como casos de estudio. El Programa de Desarrollo de la Zona de Mata (PROMATA) en el Estado de Pernambuco, Brasil, financiado por el Estado de Pernambuco en Brasil y el BID, finalizado en 2010, ha sido elegido como caso de estudio. Para la evaluación y medida del capital social se han estudiado dos periodos. Uno considerando solo los planes del proyecto, sin considerar su implantación, que se ha denominado evaluación A Priori, basada en un panel de expertos con visión de las externalidades generadas. Y otra con la participación de las partes de la comunidad después de su finalización, denomina evaluación A Posteriori, para lo cual se han entrevistado un número significativo de partes interesadas utilizando un cuestionario especialmente diseñado. Los resultados han sido procesados mediante análisis estadísticos avanzados. El proyecto PROMATA es considerado un caso de éxito en Brasil, en parte por su aproximación al desarrollo asociativo. Sin embargo las valoraciones del capital social muestran que algunas relaciones Estado-sociedad y sociedad-personas no han cambiado todo lo esperado, en oposición a las evaluaciones de satisfacción de los indicadores del proyecto. Es el efecto externo del capital social. ABSTRACT The regional development programs promoted by the national governments and international multilateral agencies, like the World Bank and the Interamerican Development Bank (BID), are oriented to public policies under which public goods, like public services and infrastructures, are supplied to underdeveloped regions. More and more evidences are pointing to the fact that success of these programs depends in a good part of externalities, which are related to the changes in the networking and values among the stakeholders in the territory. These externalities are defined as the Social Capital. As externalities, they are not directly evaluated in the projects economic and social impact, but accepted to exist and the planners of the projects do acknowledge the important of social networking. However never assessed. The objective of this thesis is to investigate and propose a way to measure and assess the social capital of a given project, and relate that with the activities of the project, with a given project and territory as base case. The Development Program in Zona da Mata (PROMATA) in the State of Pernambuco, Brazil, funded by the Brazil State and the BID, ended in 2010, was chosen as the base case. For the assessment of the social capital two periods in time where studied. One considering only the project program named a priori evaluation and based in a panel of experts, which are aware of the possible externalities of the project. Other, considering the stakeholders view after the project ended, named posterior evaluation, which required interviewing a number of stakeholders using a specially designed questionnaire. The results were processed using advanced statistical techniques. PROMATA is considered a success case story in Brazil, in part for its social networking approach. However when the social capital is assessed there are areas of state-society and society-community relations not that well transformed, as the satisfaction research of the project indicators. This unforeseen externality is the social capital effect.

Pulse-Shape Analysis of PDM-QPSK Modulation Formats for 100 and 200 Gb/s DWDM transmissions

Advanced optical modulation format polarization-division multiplexed quadrature phase shift keying (PDM-QPSK) has become a key ingredient in the design of 100 and 200-Gb/s dense wavelength-division multiplexed (DWDM) networks. The performance of this format varies according to the shape of the pulses employed by the optical carrier: non-return to zero (NRZ), return to zero (RZ) or carrier-suppressed return to zero (CSRZ). In this paper we analyze the tolerance of PDM-QPSK to linear and nonlinear optical impairments: amplified spontaneous emission (ASE) noise, crosstalk, distortion by optical filtering, chromatic dispersion (CD), polarization mode dispersion (PMD) and fiber Kerr nonlinearities. RZ formats with a low duty cycle value reduce pulse-to-pulse interaction obtaining a higher tolerance to CD, PMD and intrachannel nonlinearities.

TweetAlert: Sistema de análisis semántico de la voz de los ciudadanos en redes sociales en la ciudad del futuro

En este artículo se presenta un sistema automático de almacenamiento, análisis y visualización de información semántica extraída de mensajes de Twitter, diseñado para proporcionar a las administraciones públicas una herramienta para detectar y analizar de una manera sencilla y rápida los patrones de comportamiento de los ciudadanos, su opinión acerca de los servicios públicos, la percepción de la ciudad, los eventos de interés, etc. Además, puede ser usado como un sistema de alerta temprana, mejorando la eficiencia y rapidez de actuación de los sistemas de emergencia.

Análisis semántico de la opinión de los ciudadanos en redes sociales en la ciudad del futuro

En este artículo se presenta un sistema automático de almacenamiento, análisis y visualización de información semántica extraída de mensajes de Twitter, diseñado para proporcionar a las administraciones públicas una herramienta para detectar y analizar de una manera sencilla y rápida los patrones de comportamiento de los ciudadanos, su opinión acerca de los servicios públicos, la percepción de la ciudad, los eventos de interés, etc. Además, puede ser usado como un sistema de alerta temprana, mejorando la eficiencia y rapidez de actuación de los sistemas de emergencia.

Formulación de incentivos óptimos y viables para la mejora de la seguridad vial en concesiones de carreteras

La evolución de los roles de la Administración y empresas en la prestación de servicios públicos, así como las crecientes restricciones presupuestarias para financiarlos, están propiciando una cada vez mayor utilización del sistema concesional para la financiación y gestión de carreteras. Ante esta situación, cabe cuestionarse si la regulación de las prestaciones a obtener se está introduciendo de forma adecuada en los contratos. Uno de los aspectos más relevantes en este sentido es el relacionado con la seguridad de la infraestructura, sobre el cual la empresa concesionaria tiene capacidad de actuación pero, en un sentido económico estricto, pocos incentivos para mejorarla. Todo ello a pesar de los elevados costes sociales derivados de la accidentalidad. Esta tesis analiza la idoneidad de los indicadores e incentivos de seguridad vial que se vienen aplicando en concesiones de carreteras, encontrándose una gran heterogeneidad e incluso incorrecciones técnicas en su formulación. Además se pone de manifiesto la poca vinculación que tienen con la estructura de costes y beneficios de las actuaciones de mejora de seguridad vial, por lo que su introducción en los contratos resulta anodina. Con el objeto de superar esta situación, en esta tesis se analizan en profundidad los aspectos que intervienen en la formulación de indicadores e incentivos de seguridad vial. De este análisis se deduce la ecuación que liga, por tipología de carretera, el beneficio social derivado del nivel de seguridad de la carretera y el coste para alcanzarlo. A través de esta ecuación se determina el nivel de seguridad óptimo desde el punto de vista económico‐social. La investigación continúa extrapolando métodos de la teoría microeconómica de incentivos al campo de las concesiones de carreteras, a fin de determinar la formulación del incentivo de seguridad vial teóricamente óptimo. Asimismo, la tesis toma en consideración la experiencia en la aplicación práctica de incentivos en concesiones vigentes, realizándose una propuesta para superar las controversias que se están produciendo actualmente en España. Además, se ha simulado la aplicación de la formulación propuesta a diversas concesiones con un doble objetivo: verificar la viabilidad económica de su aplicación y corroborar en qué medida se adecua mejor al óptimo económico‐social. Como resultado, se proponen un indicador y un incentivo concretos que inducen a las concesionarias a orientar su gestión hacia la consecución del nivel de seguridad vial óptimo desde el punto de vista económico‐social, todo ello dentro de un marco de viabilidad presupuestaria. Changes in the roles of Government and the Private Sector in the provision of public services along with the budget constraints to finance them are resulting in an increasing use of the concession system for financing and managing roads. Taking this into account, the question is whether the regulation of quality criteria is being properly introduced in the contracts or not. One of the most important aspects at this respect is the road safety. On the one hand, concessionaires are able to manage this aspect up to a point. On the other hand, from an strict economic point of view, they have little incentive to improve it, despite the high social costs of accidents. This thesis has analyzed the suitability of indicators and incentives usually introduced in road concession contracts, finding high heterogeneity, and even technical inaccuracies on their formulation. It has also been found the lack of connection between these incentives and the costs of measures to improve road safety, therefore they are not expected to fulfil their purpose. In order to overcome this situation, this thesis firstly analyzes in depth the issues involved in the development of road safety indicators and incentives. This analysis yields the equation which links the social benefit derived from the level of road safety and the cost to achieve it. In its turn, through this equation it is possible to meet the optimal road safety level from the socio‐economic point of view. Secondly, this thesis extrapolates microeconomic methods to the field of highway concessions, with the aim of determining the formulation of the optimal road safety incentive. Furthermore, the thesis takes into account the experience in the practical application of incentives on existing concessions, performing a proposal to settle the disputes between concessionaires and the Public Administrations. Finally, the thesis simulates the implementation of the proposed indicator and incentive to real concessions with the aim of verifying the economic feasibility of their application and confirming how they match the socio‐economic optimum. As a result, this thesis proposes an indicator and incentive that induce companies to drive the management of the concession towards achieving the optimal road safety level, all within a framework of the budgetary feasibility.

Temperature performance of AlGaN/GaN MOS-HEMTs on Si substrates using Gd2O3 as gate dielectric

GaN based high electron mobility transistors have draw great attention due to its potential in high temperature, high power and high frequency applications [1, 2]. However, significant gate leakage current is still one of the issues which need to be solved to improve the performance and reliability of the devices [3]. Several research groups have contributed to solve this problem by using metal–oxide–semiconductor HEMTs (MOSHEMTs), with a thin dielectric layer, such as SiO2 [4], Al2O3 [5], HfO2 [6] and Gd2O3 [7] between the gate and the barrier layer on AlGaN/GaN heterostructures. Gd2O3 has shown low interfacial density of states(Dit) with GaN and a high dielectric constant and low electrical leakage currents [8], thus is considered as a promising candidate for the gate dielectrics on GaN. MOS-HEMTs using Gd2O3 grown by electron-beam heating [7] or molecular beam epitaxy (MBE) [8] on GaN or AlGan/GaN structure have been investigated, but further research is still needed in Gd2O3 based AlGaN/GaN MOSHEMTs.