Development of an Analytic Nodal Diffusion Solver in Multigroups for 3D Reactor Cores with Rectangular or Hexagonal Assemblies.

More accurate modelling of physical phenomena involved in present and future nuclear reactors requires a multi-scale and multi-physics approach. This challenge can be accomplished by the coupling of best-estimate core-physics, thermal-hydraulics and multi-physics solvers. In order to make viable that coupling, the current trends in reactor simulations are along the development of a new generation of tools based on user-friendly, modular, easily linkable, faster and more accurate codes to be integrated in common platforms. These premises are in the origin of the NURESIM Integrated Project within the 6th European Framework Program, which is envisaged to provide the initial step towards a Common European Standard Software Platform for nuclear reactors simulations. In the frame of this project and to reach the above-mentioned goals, a 3-D multigroup nodal solver for neutron diffusion calculations called ANDES (Analytic Nodal Diffusion Equation Solver) has been developed and tested in-depth in this Thesis. ANDES solves the steady-state and time-dependent neutron diffusion equation in threedimensions and any number of energy groups, utilizing the Analytic Coarse-Mesh Finite-Difference (ACMFD) scheme to yield the nodal coupling equations. It can be applied to both Cartesian and triangular-Z geometries, so that simulations of LWR as well as VVER, HTR and fast reactors can be performed. The solver has been implemented in a fully encapsulated way, enabling it as a module to be readily integrated in other codes and platforms. In fact, it can be used either as a stand-alone nodal code or as a solver to accelerate the convergence of whole core pin-by-pin code systems. Verification of performance has shown that ANDES is a code with high order definition for whole core realistic nodal simulations. In this paper, the methodology developed and involved in ANDES is presented

Do emerging and developed countries differ in terms of sustainable performance? Analysis of board, ownership and country-level factors

[EN] This paper aims to provide insights into the environmental, social and governance (ESG) performance of firms from emerging and developed countries relative to their control mechanisms and institutional framework. The main objective is to determine which of these board, ownership and country-level drivers exert the greatest explanatory power in ESG performance. In other words, this paper examines the behaviour of the board of directors, ownership and the effect of institutional pressure. Using a sample of 69 461 firm-year observations from 2012 to 2018, and following a two-stage analysis model, the results point to interesting findings for both blocks of countries. In emerging environments, the country effect prevails and the positive effect of the board of directors guarantees its efficiency, while in developed countries, the main mechanism affecting ESG performance is the board of directors, with the ownership effect also playing a key role

A Bandwidth-Efficient Dissemination Scheme of Non-Safety Information in Urban VANETs

The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application.This work was partially founded by the Spanish Ministry of Science and Innovation within the framework of projects TEC2010-20572-C02-01 “CONSEQUENCE” and TEC2014-54335-C4-2-R “INRISCO” and by the Regional Government of Madrid within the “eMadrid” project under Grants S2009/TIC-1650 and S2013/ICE-2715, including the costs to publish in open access

Supporting L3 femtocell mobility using the MOBIKE protocol

Proceeding of ACCESS 2011, The Second International Conference on Access Networks, Luxembourg City, Luxembourg, June 19-24, 2011Femtocells can be used to improve the indoor coverage and bandwidth of 3G cellular networks in homes and buildings. They are designed to be placed in a fixed location. However, their use would also be interesting in mobile environments such as public transportation systems. This paper studies the mobility limitations at the layer 3 and suggests an approach to support mobility on femtocell networks. This solution employs the protocols already defined in the femtocell architecture, minimizing thus the impact on it.This work has been supported by the Spanish Ministry of Science and Innovation, CONSEQUENCE project (TEC2010- 20572-C02-01) and partially supported by the Madrid regional community project CCG10-UC3M/TIC-4992

The Role of Vitamin C in the Protection and Modulation of Genotoxic Damage Induced by Metals Associated with Oxidative Stress

This chapter reviews the effects of vitamin C on metal-induced genotoxicity. By focusing on cutting-edge studies, including our own results in experiments with vanadium(V) and chromium(VI), the suggestion that vitamin C can be used effectively to protect against or reduce the genotoxic effects induced by metal exposure by suppressing oxidative stress is particularly explored. After explaining the chemical mechanisms involved in oxidative stress associated with heavy metals, this chapter discusses the various proposals regarding the physiological processes of vitamin C at the molecular level, its relationship with oxidative stress, levels of 8-hydroxydeoxyguanosine (8-OH-dG, 7,8-dihy-dro-8-oxodeoxyguanosine) and apoptosis, and its role in the protection and modulation of DNA damage, as well as how they fit with our own results that showed an increase in apoptosis and 8-OH-dG when vitamin C was administered in addition to the metallic compounds. The relevant gaps in our understanding of the role of vitamin C with regard to these issues are highlighted, as well as the key importance of its clinical use, and ultimately, human health

The Role of Green Tea Polyphenols in the Protection from Hexavalent Chromium-Induced Genotoxic Damage

In this chapter, the proposal that green tea polyphenols can be used effectively to protect against genotoxic effects associated with hexavalent chromium (Cr(VI)) exposure is analyzed. After explaining the chemical mechanisms involved in oxidative stress associated with the reduction of Cr(VI) compounds, the relationship between green tea polyphenols and oxidative stress is analyzed. Particular emphasis is given in elucidating how these proposals fit with our own experimental results with green tea polyphenols and Cr(VI) compounds, which show an increase of apoptotic cells and a decrease in micronucleus frequency. Finally, the gaps in our understanding of the role of green tea and its polyphenols, as well as their key importance to human health, are highlighted

Los desafíos ambientales de las poblaciones indígenas en el Ártico

The special vulnerability of indigenous peoples in the Arctic has increased in recent decades due to various environmental challenges. On the one hand, global warming is causing the melting of this region and the lack of important natural resources for these peoples. These changes will not only affect their quality of life, but also to their cultural identity, since climatic conditions in which its existence has developed over the centuries are changing very rapidly. On the other hand, the European Union has adopted a series of trade measures prohibiting the importation and marketing of seal products in its territory, although it allows the trade of seal products when captured by Inuit communities. The exception was introduced to protect them since seal hunting is an important element of their culture and their survival, but its compatibility with the law of the World Trade Organization has been challengedLa especial vulnerabilidad de los pueblos indígenas del Ártico se ha visto acrecentada en las últimas décadas debido a distintos desafíos medioambientales. Por un lado, el calentamiento global es causante del deshielo de esta región y la carencia de recursos naturales importantes para estas poblaciones. Estos cambios no solo afectan su calidad de vida, sino también su identidad cultural, ya que las condiciones climáticas en las que su existencia se ha desarrollado durante siglos están cambiando muy rápidamente. Por otro lado, la Unión Europea ha adoptado una serie de medidas comerciales que prohíben la importación y comercialización de los productos de focas en su territorio, aunque se permite el comercio de los productos de focas capturadas por las comunidades Inuit. La excepción fue introducida para protegerlos, ya que la caza de focas es un elemento importante de su cultura y supervivencia, pero su compatibilidad con el Derecho de la Organización Mundial de Comercio ha sido cuestionad

Schemes for multi-hop dissemination of non-safety information in VANETs

Vehicular Ad Hoc Networks (VANETs) are a special case of Mobile Ad Hoc Network (MANET), whose nodes are vehicles and occasional fixed devices with communication capabilities. What makes them special is the limited range of possible movements of the mobile nodes (they can only travel on the existing roads or rails) and their high speed. The potential applications in this new type of network are almost endless. Researchers have typically classified them in four groups: active safety, public service support, improved driving and business/entertainment. The communication patterns that they require are varied, being information dissemination one of them. It is aimed at reaching a group of vehicles in an area that is larger than the reception range of a single node, so that a multi-hop broadcast is necessary. It can take multiple forms depending on the type of message. For example, a warning caused by a sudden brake requires a fast and reliable dissemination, whereas a blocked route announcement is tolerant to delays up to a few seconds and may miss some target without risking safety. The work in this PhD thesis is focused on this last type of use. The objective is to create schemes that would allow for the multi-hop dissemination of messages that do not have hard delay and delivery requirements (typically, any non-safety information). Our goals for this solution are four. First, we want it to be useful in roadways as well as inside cities. Vehicles movements and the occurrence of obstacles to the signal propagation are very different in both scenarios and so we need to adapt it to both. Second, we want it to be independent of infrastructure. The cost of deploying fixed units along every road and street is high and it may take a long time until there is global coverage. Our intention is that this solution can be used regardlessly of the deployment point. In addition, it must avoid the broadcast storm problem by reducing as much as possible the number of generated duplicates. Lastly, the scheme needs to cope with intermittent partitions in the vehicular network. Implementing a store-carry-forward mechanism that allows a message reach disconnected groups of vehicles inside the destination area rises the number of necessary duplicates. In order to achieve the aforementioned goals, we first study how typical infrastructure-less dissemination schemes from the state of the art in MANETs, plus a new specific one, apply to VANETs. According to their results in relation to a series of metrics, we learn that the distance-based scheme is the one that best meets our requirements. We select it to create an optimized scheme for the two existing scenarios-roadways and urban areas. Regarding the adaptation for roadways, we begin by optimizing the scheme so that its forwarding ratio is as close to the minimum as possible, and analyzing its average per-hop delay in a connected network (i.e., there is at least one feasible route between any two nodes in the network). Next, we study how to add a custom store-carry-forward mechanism that, with minimal additions, manages to overcome short-lived network partitions. We validate the addition and the complete scheme under different channel loads and in contrast with a well-known protocol aimed at the same type of traffic, DV-CAST. Our work on the version for urban scenarios parts from the assumption that we need to detect junctions and react accordingly in order to spread the dissemination in new directions and reach as many vehicles as possible. We create two different modifications of the basic distance-based scheme, each using a different method to detect intersections, and test them along with the basic one. This first step leads us to discovering that it is not necessary to detect intersections in order to achieve good results. Then, similarly to the process for the roadway scenario, we work on optimizing the scheme and creating a suitable store-carry-forward mechanism. We follow the same reasoning but this time we consider three different options for subsequent retransmissions. We test each version of the scheme throughly via simulations using real city maps and compare the results to those of the urban counterpart of DV-CAST, named UV-CAST. We use validated simulators as ns-2 and the Veins framework for testing realistically the different stages of our work. The performance of the resulting schemes meet our requirements to a high degree and so we consider that we have fulfilled our goals. In addition, the work done so far opens the door to new lines of research that are either the natural consequence or an application of our achievements.La expresión inglesa Vehicular Ad Hoc Networks (VANETs) nombra a un tipo especial de Mobile Ad Hoc Network (MANET), cuyos nodos son vehículos y, ocasionalmente, dispositivos fijos con capacidad de comunicación. Lo que las hace especiales es el rango limitado de movimientos posibles para los nodos móviles (ya que sólo pueden viajar por las vías existentes) y su alta velocidad. Las aplicaciones potenciales de este nuevo tipo de red son casi infinitas. La comunidad investigadora las ha clasificado típicamente en cuatro grupos: seguridad activa, apoyo a servicios públicos, asistencia a la conducción y negocios/entretenimiento. Los patrones de comunicación que precisan son variados, siendo la diseminación de información uno de ellos. Su objetivo es alcanzar a un grupo de vehículos en un área mayor que el de la cobertura alcanzada por un nodo, de modo que es necesaria una difusión multisalto. Esta puede tomar múltiples formas dependiendo del tipo de mensaje. Por ejemplo, una alarma provocada por un frenazo brusco requiere una diseminación rápida y confiable, mientras que un aviso de calle cortada es tolerante a retardos de hasta algunos segundos y si no alcanza a algún destinatario no supone un riesgo para la seguridad. El trabajo contenido en esta tesis se enfoca en este último caso de uso. La meta es crear esquemas que permitan la diseminación multisalto de mensajes que no tienen requisitos fuertes en cuanto a retardo y entrega (típicamente, cualquier información no relacionada con la seguridad). Nuestros objetivos para esta solución son cuatro. Primero, queremos que sea útil en carretera así como en ciudad. Los movimientos de los vehículos y la existencia de obstáculos para la propagación de la señal son muy diferentes en ambos escenarios y por tanto necesitamos adaptarla a ambos. Segundo, queremos que no dependa de infraestructura. El coste de desplegar unidades fijas a lo largo de cada calle y carretera es alto, y puede llevar un largo tiempo hasta que haya cobertura global. Nuestra intención es que esta solución pueda ser usada en cualquier punto del proceso de despliegue. Además, debe evitar el problema conocido como “tormenta broadcast”, reduciendo en la medida de lo posible el número de duplicados generados. Por último, el esquema necesita hacer frente a particiones intermitentes de la red vehicular. Implementar un mecanismo de los llamados “store-carry-forward” (guardar-llevar-reenviar), que permita a un mensaje llegar a grupos desconectados de vehículos dentro de la zona de destino, aumenta el número de duplicados necesarios. Para conseguir estos objetivos, primero estudiamos cómo esquemas típicos de diseminación sin apoyo de infraestructura, tomados del estado del arte en MANETs, más uno nuevo y específico, se pueden aplicar en VANETs. De acuerdo con los resultados en relación con una serie de métricas, hemos aprendido que el esquema basado en distancia es el que mejor cubre nuestros requisitos. Seleccionamos este para crear un esquema optimizado para los dos tipos de escenarios existentes: carretera (entorno interurbano) y ciudad (entorno urbano). En cuanto a la adaptación al entorno interurbano, comenzamos optimizando el esquema de modo que su tasa de reenvío esté tan cerca del mínimo como sea posible, y analizando su retardo medio por salto en una red conectada (es decir, que hay al menos una ruta posible entre dos nodos cualesquiera de la red). A continuación, estudiamos cómo añadir un mecanismo “store-carry-forward" específico para nuestra solución que, con cambios mínimos, consiga superar particiones de red breves. Validamos este añadido y el esquema completo bajo diferentes cargas de canal y en contraste con un conocido protocolo para este mismo tipo de tráfico, DV-CAST. Nuestro trabajo en la versión para escenarios urbanos parte del supuesto de que necesitamos detectar intersecciones y reaccionar en consecuencia para poder extender la diseminación en nuevas direcciones y alcanzar tantos vehículos como sea posible. Creamos dos modificaciones del esquema basado en distancia, cada una en base a un método distinto para detectar cruces, y las probamos junto con el esquema básico. Este primer paso nos lleva a descubrir que no es necesaria dicha detección para poder conseguir buenos resultados. Después, de forma similar al proceso que seguimos para el escenario de carretera, trabajamos en optimizar el esquema y crear un mecanismo “store-carry-forward" apropiado. Seguimos el mismo razonamiento pero en esta ocasión consideramos tres opciones diferentes para las repetidas retransmisiones. Probamos cada versión del esquema concienzudamente con simulaciones, utilizando mapas reales de ciudades, y comparamos los resultados con los del equivalente urbano de DV-CAST, llamado UV-CAST. Usamos simuladores validados como ns-2 y Veins para probar de forma realista las diferentes etapas de nuestro trabajo. Las prestaciones de los esquemas resultantes cumplen con nuestros requisitos en un alto grado, por lo que consideramos que hemos conseguido alcanzar nuestros objetivos. Además, el trabajo realizado hasta el momento abre la puerta a nuevas líneas de investigación que son, bien consecuencia natural, bien aplicación de nuestros logros.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Juan Carlos Cano Escriba.- Secretario: Florina Almenares Mendoza.- Vocal: José Marta Barcelo Ordina

Aplicando Eurored y Studium a asignaturas de Economía Financiera y elaboración de materiales para los alumnos

Memoria ID-002. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2008-2009.El principal resultado de esta ayuda ha sido el posibilitar una mayor agilidad en el desarrollo de las exposiciones docentes en el aula, al anticipar y facilitar el seguimiento de las explicaciones por parte de los alumnos. Sin duda, ello también es fruto de la labor de años. Además de haber obtenido en dos ocasiones el reconocimiento por la Innovación docente que se estaba realizando por el Vicerrectorado de Planificación Estratégica y Calidad de esta Universidad, este año se han seguido elaborando diversos materiales enfocados a la adaptación de las asignaturas que imparte la solicitante al Espacio Europeo de Educación Superior, labores de recopilación de documentación, elaboración de esquemas y desarrollos en formato Word y Power Point para los alumnos en las plataformas dedicadas a fomentar el conocimiento y la participación del alumno (http://web.usal.es/~beloga/ y http://eudored.usal.es)