VISIONS Vehicular communication Improvement : solution based on IMS Operational Nodes and Services

Digital services and communications in vehicular scenarios provide the essential assets to improve road transport in several ways like reducing accidents, improving traffic efficiency and optimizing the transport of goods and people. Vehicular communications typically rely on VANET (Vehicular Ad hoc Networks). In these networks vehicles communicate with each other without the need of infrastructure. VANET are mainly oriented to disseminate information to the vehicles in certain geographic area for time critical services like safety warnings but present very challenging requirements that have not been successfully fulfilled nowadays. Some of these challenges are; channel saturation due to simultaneous radio access of many vehicles, routing protocols in topologies that vary rapidly, minimum quality of service assurance and security mechanisms to efficiently detect and neutralize malicious attacks. Vehicular services can be classified in four important groups: Safety, Efficiency, Sustainability and Infotainment. The benefits of these services for the transport sector are clear but many technological and business challenges need to be faced before a real mass market deployment. Service delivery platforms are not prepared for fulfilling the needs of this complex environment with restrictive requirements due to the criticism of some services To overcome this situation, we propose a solution called VISIONS ���Vehicular communication Improvement: Solution based on IMS Operational Nodes and Services���. VISIONS leverages on IMS subsystem and NGN enablers, and follows the CALM reference Architecture standardized by ISO. It also avoids the use of Road Side Units (RSUs), reducing complexity and high costs in terms of deployment and maintenance. We demonstrate the benefits in the following areas: 1. VANET networks efficiency. VISIONS provide a mechanism for the vehicles to access valuable information from IMS and its capabilities through a cellular channel. This efficiency improvement will occur in two relevant areas: a. Routing mechanisms. These protocols are responsible of carrying information from a vehicle to another (or a group of vehicles) using multihop mechanisms. We do not propose a new algorithm but the use of VANET topology information provided through our solution to enrich the performance of these protocols. b. Security. Many aspects of security (privacy, key, authentication, access control, revocation mechanisms, etc) are not resolved in vehicular communications. Our solution efficiently disseminates revocation information to neutralize malicious nodes in the VANET. 2. Service delivery platform. It is based on extended enablers, reference architectures, standard protocols and open APIs. By following this approach, we reduce costs and resources for service development, deployment and maintenance. To quantify these benefits in VANET networks, we provide an analytical model of the system and simulate our solution in realistic scenarios. The simulations results demonstrate how VISIONS improves the performance of relevant routing protocols and is more efficient neutralizing security attacks than the widely proposed solutions based on RSUs. Finally, we design an innovative Social Network service based in our platform, explaining how VISIONS facilitate the deployment and usage of complex capabilities. RESUMEN Los servicios digitales y comunicaciones en entornos vehiculares proporcionan herramientas esenciales para mejorar el transporte por carretera; reduciendo el n��mero de accidentes, mejorando la eficiencia del tr��fico y optimizando el transporte de mercanc��as y personas. Las comunicaciones vehiculares generalmente est��n basadas en redes VANET (Vehicular Ad hoc Networks). En dichas redes, los veh��culos se comunican entre s�� sin necesidad de infraestructura. Las redes VANET est��n principalmente orientadas a difundir informaci��n (por ejemplo advertencias de seguridad) a los veh��culos en determinadas zonas geogr��ficas, pero presentan unos requisitos muy exigentes que no se han resuelto con ��xito hasta la fecha. Algunos de estos retos son; saturaci��n del canal de acceso de radio debido al acceso simult��neo de m��ltiples veh��culos, la eficiencia de protocolos de encaminamiento en topolog��as que var��an r��pidamente, la calidad de servicio (QoS) y los mecanismos de seguridad para detectar y neutralizar los ataques maliciosos de manera eficiente. Los servicios vehiculares pueden clasificarse en cuatro grupos: Seguridad, Eficiencia del tr��fico, Sostenibilidad, e Infotainment (informaci��n y entretenimiento). Los beneficios de estos servicios para el sector son claros, pero es necesario resolver muchos desaf��os tecnol��gicos y de negocio antes de una implementaci��n real. Las actuales plataformas de despliegue de servicios no est��n preparadas para satisfacer las necesidades de este complejo entorno con requisitos muy restrictivos debido a la criticidad de algunas aplicaciones. Con el objetivo de mejorar esta situaci��n, proponemos una soluci��n llamada VISIONS ���Vehicular communication Improvement: Solution based on IMS Operational Nodes and Services���. VISIONS se basa en el subsistema IMS, las capacidades NGN y es compatible con la arquitectura de referencia CALM estandarizado por ISO para sistemas de transporte. Tambi��n evita el uso de elementos en las carreteras, conocidos como Road Side Units (RSU), reduciendo la complejidad y los altos costes de despliegue y mantenimiento. A lo largo de la tesis, demostramos los beneficios en las siguientes ��reas: 1. Eficiencia en redes VANET. VISIONS proporciona un mecanismo para que los veh��culos accedan a informaci��n valiosa proporcionada por IMS y sus capacidades a trav��s de un canal de celular. Dicho mecanismo contribuye a la mejora de dos ��reas importantes: a. Mecanismos de encaminamiento. Estos protocolos son responsables de llevar informaci��n de un veh��culo a otro (o a un grupo de veh��culos) utilizando m��ltiples saltos. No proponemos un nuevo algoritmo de encaminamiento, sino el uso de informaci��n topol��gica de la red VANET a trav��s de nuestra soluci��n para enriquecer el funcionamiento de los protocolos m��s relevantes. b. Seguridad. Muchos aspectos de la seguridad (privacidad, gesti��n de claves, autenticaci��n, control de acceso, mecanismos de revocaci��n, etc) no est��n resueltos en las comunicaciones vehiculares. Nuestra soluci��n difunde de manera eficiente la informaci��n de revocaci��n para neutralizar los nodos maliciosos en la red. 2. Plataforma de despliegue de servicios. Est�� basada en capacidades NGN, arquitecturas de referencia, protocolos est��ndar y APIs abiertos. Siguiendo este enfoque, reducimos costes y optimizamos procesos para el desarrollo, despliegue y mantenimiento de servicios vehiculares. Para cuantificar estos beneficios en las redes VANET, ofrecemos un modelo de anal��tico del sistema y simulamos nuestra soluci��n en escenarios realistas. Los resultados de las simulaciones muestran c��mo VISIONS mejora el rendimiento de los protocolos de encaminamiento relevantes y neutraliza los ataques a la seguridad de forma m��s eficientes que las soluciones basadas en RSU. Por ��ltimo, dise��amos un innovador servicio de red social basado en nuestra plataforma, explicando c��mo VISIONS facilita el despliegue y el uso de las capacidades NGN.

Low-resource language recognition using a fusion of phoneme posteriorgram counts, acoustic and glottal-based i-vectors

This paper presents a description of our system for the Albayzin 2012 LRE competition. One of the main characteristics of this evaluation was the reduced number of available files for training the system, especially for the empty condition where no training data set was provided but only a development set. In addition, the whole database was created from online videos and around one third of the training data was labeled as noisy files. Our primary system was the fusion of three different i-vector based systems: one acoustic system based on MFCCs, a phonotactic system using trigrams of phone-posteriorgram counts, and another acoustic system based on RPLPs that improved robustness against noise. A contrastive system that included new features based on the glottal source was also presented. Official and postevaluation results for all the conditions using the proposed metrics for the evaluation and the Cavg metric are presented in the paper.

Monitoring visual attention on a neurorehabilitation environment based on interactive video

The use of new technologies in neurorehabilitation has led to higher intensity rehabilitation processes, extending therapies in an economically sustainable way. Interactive Video (IV) technology allows therapists to work with virtual environments that reproduce real situations. In this way, patients deal with Activities of the Daily Living (ADL) immersed within enhanced environments [1]. These rehabilitation exercises, which focus in re-learning lost functions, will try to modulate the neural plasticity processes [2]. This research presents a system where a neurorehabilitation IV-based environment has been integrated with an eye-tracker device in order to monitor and to interact using visual attention. While patients are interacting with the neurorehabilitation environment, their visual behavior is closely related with their cognitive state, which in turn mirrors the brain damage condition suffered by them [3] [4]. Patients��� gaze data can provide knowledge on their attention focus and their cognitive state, as well as on the validity of the rehabilitation tasks proposed [5].

Massively parallelizable list-mode reconstruction using a Monte Carlo-based elliptical Gaussian model

Purpose: A fully three-dimensional (3D) massively parallelizable list-mode ordered-subsets expectation-maximization (LM-OSEM) reconstruction algorithm has been developed for high-resolution PET cameras. System response probabilities are calculated online from a set of parameters derived from Monte Carlo simulations. The shape of a system response for a given line of response (LOR) has been shown to be asymmetrical around the LOR. This work has been focused on the development of efficient region-search techniques to sample the system response probabilities, which are suitable for asymmetric kernel models, including elliptical Gaussian models that allow for high accuracy and high parallelization efficiency. The novel region-search scheme using variable kernel models is applied in the proposed PET reconstruction algorithm. Methods: A novel region-search technique has been used to sample the probability density function in correspondence with a small dynamic subset of the field of view that constitutes the region of response (ROR). The ROR is identified around the LOR by searching for any voxel within a dynamically calculated contour. The contour condition is currently defined as a fixed threshold over the posterior probability, and arbitrary kernel models can be applied using a numerical approach. The processing of the LORs is distributed in batches among the available computing devices, then, individual LORs are processed within different processing units. In this way, both multicore and multiple many-core processing units can be efficiently exploited. Tests have been conducted with probability models that take into account the noncolinearity, positron range, and crystal penetration effects, that produced tubes of response with varying elliptical sections whose axes were a function of the crystal's thickness and angle of incidence of the given LOR. The algorithm treats the probability model as a 3D scalar field defined within a reference system aligned with the ideal LOR. Results: This new technique provides superior image quality in terms of signal-to-noise ratio as compared with the histogram-mode method based on precomputed system matrices available for a commercial small animal scanner. Reconstruction times can be kept low with the use of multicore, many-core architectures, including multiple graphic processing units. Conclusions: A highly parallelizable LM reconstruction method has been proposed based on Monte Carlo simulations and new parallelization techniques aimed at improving the reconstruction speed and the image signal-to-noise of a given OSEM algorithm. The method has been validated using simulated and real phantoms. A special advantage of the new method is the possibility of defining dynamically the cut-off threshold over the calculated probabilities thus allowing for a direct control on the trade-off between speed and quality during the reconstruction.

Operational costs and reliability in a large rural electrification programme based on solar home systems

Experiences in decentralized rural electrification programmes using solar home systems have suffered difficulties during the operation and maintenance phase, due in many cases, to the underestimation of the maintenance cost, because of the decentralized character of the activity, and also because the reliability of the solar home system components is frequently unknown. This paper reports on the reliability study and cost characterization achieved in a large photovoltaic rural electrification programme carried out in Morocco. The paper aims to determinate the reliability features of the solar systems, focusing in the in-field testing for batteries and photovoltaic modules. The degradation rates for batteries and PV modules have been extracted from the in-field experiments. On the other hand, the main costs related to the operation and maintenance activity have been identified with the aim of establishing the main factors that lead to the failure of the quality sustainability in many rural electrification programmes.

Explicit Expressions for Solar Panel Equivalent Circuit Parameters Based on Analytical Formulation and the Lambert W-Function

Due to the high dependence of photovoltaic energy efficiency on environmental conditions (temperature, irradiation...), it is quite important to perform some analysis focusing on the characteristics of photovoltaic devices in order to optimize energy production, even for small-scale users. The use of equivalent circuits is the preferred option to analyze solar cells/panels performance. However, the aforementioned small-scale users rarely have the equipment or expertise to perform large testing/calculation campaigns, the only information available for them being the manufacturer datasheet. The solution to this problem is the development of new and simple methods to define equivalent circuits able to reproduce the behavior of the panel for any working condition, from a very small amount of information. In the present work a direct and completely explicit method to extract solar cell parameters from the manufacturer datasheet is presented and tested. This method is based on analytical formulation which includes the use of the Lambert W-function to turn the series resistor equation explicit. The presented method is used to analyze commercial solar panel performance (i.e., the current-voltage���I-V���curve) at different levels of irradiation and temperature. The analysis performed is based only on the information included in the manufacturer���s datasheet.

The Role of Knowledge Modeling Techniques in Software Development: A General Approach Based on a Knowledge Management Tool

The aim of the paper is to discuss the use of knowledge models to formulate general applications. First, the paper presents the recent evolution of the software field where increasing attention is paid to conceptual modeling. Then, the current state of knowledge modeling techniques is described where increased reliability is available through the modern knowledge acquisition techniques and supporting tools. The KSM (Knowledge Structure Manager) tool is described next. First, the concept of knowledge area is introduced as a building block where methods to perform a collection of tasks are included together with the bodies of knowledge providing the basic methods to perform the basic tasks. Then, the CONCEL language to define vocabularies of domains and the LINK language for methods formulation are introduced. Finally, the object oriented implementation of a knowledge area is described and a general methodology for application design and maintenance supported by KSM is proposed. To illustrate the concepts and methods, an example of system for intelligent traffic management in a road network is described. This example is followed by a proposal of generalization for reuse of the resulting architecture. Finally, some concluding comments are proposed about the feasibility of using the knowledge modeling tools and methods for general application design.

Using Electronic Documents for Knowledge Acquisition and Model Maintenance

Knowledge acquisition and model maintenance are key problems in knowledge engineering to improve the productivity in the development of intelligent systems. Although historically a number of technical solutions have been proposed in this area, the recent experience shows that there is still an important gap between the way end-users describe their expertise and the way intelligent systems represent knowledge. In this paper we propose an original way to cope with this problem based on electronic documents. We propose the concept of intelligent document processor as a tool that allows the end-user to read/write a document explaining how an intelligent system operates in such a way that, if the user changes the content of the document, the intelligent system will react to these changes. The paper presents the structure of such a document based on knowledge categories derived from the modern knowledge modeling methodologies together with a number of requirements to be understandable by end-users and problem solvers.

KATS: A Knowledge Acquisition Tool Based on Electronic Document Processing

This paper describes a particular knowledge acquisition tool for the construction and maintenance of the knowledge model of an intelligent system for emergency management in the field of hydrology. This tool has been developed following an innovative approach directed to end-users non familiarized in computer oriented terminology. According to this approach, the tool is conceived as a document processor specialized in a particular domain (hydrology) in such a way that the whole knowledge model is viewed by the user as an electronic document. The paper first describes the characteristics of the knowledge model of the intelligent system and summarizes the problems that we found during the development and maintenance of such type of model. Then, the paper describes the KATS tool, a software application that we have designed to help in this task to be used by users who are not experts in computer programming. Finally, the paper shows a comparison between KATS and other approaches for knowledge acquisition.

Explicit expressions for solar panel equivalent circuit parameters based on analytical formulation and the Lambert W - Function

Due to the high dependence of photovoltaic energy efficiency on environmental conditions (temperature, irradiation...), it is quite important to perform some analysis focusing on the characteristics of photovoltaic devices in order to optimize energy production, even for small-scale users. The use of equivalent circuits is the preferred option to analyze solar cells/panels performance. However, the aforementioned small-scale users rarely have the equipment or expertise to perform large testing/calculation campaigns, the only information available for them being the manufacturer datasheet. The solution to this problem is the development of new and simple methods to define equivalent circuits able to reproduce the behavior of the panel for any working condition, from a very small amount of information. In the present work a direct and completely explicit method to extract solar cell parameters from the manufacturer datasheet is presented and tested. This method is based on analytical formulation which includes the use of the Lambert W-function to turn the series resistor equation explicit. The presented method is used to analyze the performance (i.e., the I - V curve) of a commercial solar panel at different levels of irradiation and temperature. The analysis performed is based only on the information included in the manufacturer's datasheet.

On the harmonic analysis of cup anemometer rotation speed: A principle to monitor performance and maintenance status of rotating meteorological sensors

The calibration results of one anemometer equipped with several rotors, varying their size, were analyzed. In each case, the 30-pulses pert turn output signal of the anemometer was studied using Fourier series decomposition and correlated with the anemometer factor (i.e., the anemometer transfer function). Also, a 3-cup analytical model was correlated to the data resulting from the wind tunnel measurements. Results indicate good correlation between the post-processed output signal and the working condition of the cup anemometer. This correlation was also reflected in the results from the proposed analytical model. With the present work the possibility of remotely checking cup anemometer status, indicating the presence of anomalies and, therefore, a decrease on the wind sensor reliability is revealed.

Identification of intermediate debonding damage in FRP-plated RC beams based on multi-objective particle swarm optimization without updated baseline model

Fiber reinforced polymer composites (FRP) have found widespread usage in the repair and strengthening of concrete structures. FRP composites exhibit high strength-to-weight ratio, corrosion resistance, and are convenient to use in repair applications. Externally bonded FRP flexural strengthening of concrete beams is the most extended application of this technique. A common cause of failure in such members is associated with intermediate crack-induced debonding (IC debonding) of the FRP substrate from the concrete in an abrupt manner. Continuous monitoring of the concrete?FRP interface is essential to pre- vent IC debonding. Objective condition assessment and performance evaluation are challenging activities since they require some type of monitoring to track the response over a period of time. In this paper, a multi-objective model updating method integrated in the context of structural health monitoring is demonstrated as promising technology for the safety and reliability of this kind of strengthening technique. The proposed method, solved by a multi-objective extension of the particle swarm optimization method, is based on strain measurements under controlled loading. The use of permanently installed fiber Bragg grating (FBG) sensors embedded into the FRP-concrete interface or bonded onto the FRP strip together with the proposed methodology results in an automated method able to operate in an unsupervised mode.

Numerical Simulation of the Aerodynamic Behavior of High Velocity Trains under Synthetic Crosswinds of Different Shear and Turbulence Characteristics

A numerical simulation of the aerodynamic behavior of high-speed trains under synthetic crosswinds at a 90�� yaw angle is presented. The train geometry is the aerodynamic train model (ATM). Flow description based on numerical simulations is obtained using large eddy simulation (LES) and the commercial code ANSYSFluent V14.5. A crosswind whose averaged velocity and turbulence characteristics change with distance to the ground is imposed. Turbulent fluctuations that vary temporally and spatially are simulated with TurbSim code. The crosswind boundary condition is calculated for the distance the train runs during a simulation period. The inlet streamwise velocity boundary condition is generated using Taylor?s frozen turbulence hypothesis. The model gives a time history of the force and moments acting on the train; this includes averaged values, standard deviations and extreme values. Of particular interest are the spectra of the forces and moments, and the admittance spectra. For comparison, results obtained with LES and a uniform wind velocity fluctuating in time, and results obtained with Reynolds averaged Navier Stokes equations (RANS), and the averaged wind conditions, are also presented.

Characterisation of the operation & maintenance phase in PV rural electrification programmes

Con 1.300 millones de personas en el mundo sin acceso a la electricidad (la mayor��a en entornos rurales de pa��ses empobrecidos), la energ��a solar fotovoltaica constituye una soluci��n viable t��cnica y econ��micamente para electrificar las zonas m��s remotas del planeta donde las redes el��ctricas convencionales no llegan. Casi todos los pa��ses en el mundo han desarrollado alg��n tipo de programa de electrificaci��n fotovoltaica rural durante los ��ltimos 40 a��os, principalmente los pa��ses m��s pobres, donde a trav��s de diferentes modelos de financiaci��n, se han instalado millones de sistemas solares domiciliarios (peque��os sistemas fotovoltaicos para uso dom��stico). Durante este largo per��odo, se han ido superando muchas barreras, como la mejora de la calidad de los sistemas fotovoltaicos, la reducci��n de costes, la optimizaci��n del dise��o y del dimensionado de los sistemas, la disponibilidad financiera para implantar programas de electrificaci��n rural, etc. Gracias a esto, la electrificaci��n rural descentralizada ha experimentado recientemente un salto de escala caracterizada por la implantaci��n de grandes programas con miles de sistemas solares domiciliarios e integrando largos per��odos de mantenimiento. Muchos de estos grandes programas se est��n llevando a cabo con limitado ��xito, ya que generalmente parten de supuestos e hip��tesis poco contrastadas con la realidad, comprometiendo as�� un retorno econ��mico que permita el desarrollo de esta actividad a largo plazo. En este escenario surge un nuevo reto: el de c��mo garantizar la sostenibilidad de los grandes programas de electrificaci��n rural fotovoltaica. Se argumenta que la principal causa de esta falta de rentabilidad es el imprevisto alto coste de la fase de operaci��n y mantenimiento. Cuestiones clave tales como la estructura de costes de operaci��n y mantenimiento o la fiabilidad de los componentes del sistema fotovoltaico no est��n bien caracterizados hoy en d��a. Esta situaci��n limita la capacidad de dise��ar estructuras de mantenimiento capaces de asegurar la sostenibilidad y la rentabilidad del servicio de operaci��n y mantenimiento en estos programas. Esta tesis doctoral tiene como objetivo responder a estas cuestiones. Se ha realizado varios estudios sobre la base de un gran programa de electrificaci��n rural fotovoltaica real llevado a cabo en Marruecos con m��s de 13.000 sistemas solares domiciliarios instalados. Sobre la base de este programa se ha hecho una evaluaci��n en profundidad de la fiabilidad de los sistemas solares a partir de los datos de mantenimiento recogidos durante 5 a��os con m��s de 80.000 inputs. Los resultados han permitido establecer las funciones de fiabilidad de los equipos tal y como se comportan en condiciones reales de operaci��n, las tasas de fallos y los tiempos medios hasta el fallo para los principales componentes del sistema, siendo este el primer caso de divulgaci��n de resultados de este tipo en el campo de la electrificaci��n rural fotovoltaica. Los dos principales componentes del sistema solar domiciliario, la bater��a y el m��dulo fotovoltaico, han sido analizados en campo a trav��s de una muestra de 41 sistemas trabajando en condiciones reales pertenecientes al programa solar marroqu��. Por un lado se ha estudiado la degradaci��n de la capacidad de las bater��as y por otro la degradaci��n de potencia de los m��dulos fotovoltaicos. En el caso de las bater��as, los resultados nos han permitido caracterizar la curva de degradaci��n en capacidad llegando a obtener una propuesta de nueva definici��n del umbral de vida ��til de las bater��as en electrificaci��n rural. Tambi��n sobre la base del programa solar de Marruecos se ha llevado a cabo un estudio de caracterizaci��n de los costes reales de operaci��n y mantenimiento a partir de la base de datos de contabilidad del programa registrados durante 5 a��os. Los resultados del estudio han permitido definir cu��les son costes que m��s incidencia tienen en el coste global. Se han obtenido los costes unitarios por sistema instalado y se han calculado los montantes de las cuotas de mantenimiento de los usuarios para garantizar la rentabilidad de la operaci��n y mantenimiento. Finalmente, se propone un modelo de optimizaci��n matem��tica para dise��ar estructuras de mantenimiento basado en los resultados de los estudios anteriores. La herramienta, elaborada mediante programaci��n lineal entera mixta, se ha aplicado al programa marroqu�� con el fin de validar el modelo propuesto. ABSTRACT With 1,300 million people worldwide deprived of access to electricity (mostly in rural environments), photovoltaic solar energy has proven to be a cost���effective solution and the only hope for electrifying the most remote inhabitants of the planet, where conventional electric grids do not reach because they are unaffordable. Almost all countries in the world have had some kind of rural photovoltaic electrification programme during the past 40 years, mainly the poorer countries, where through different organizational models, millions of solar home systems (small photovoltaic systems for domestic use) have been installed. During this long period, many barriers have been overcome, such as quality enhancement, cost reduction, the optimization of designing and sizing, financial availability, etc. Thanks to this, decentralized rural electrification has recently experienced a change of scale characterized by new programmes with thousands of solar home systems and long maintenance periods. Many of these large programmes are being developed with limited success, as they have generally been based on assumptions that do not correspond to reality, compromising the economic return that allows long term activity. In this scenario a new challenge emerges, which approaches the sustainability of large programmes. It is argued that the main cause of unprofitability is the unexpected high cost of the operation and maintenance of the solar systems. In fact, the lack of a paradigm in decentralized rural services has led to many private companies to carry out decentralized electrification programmes blindly. Issues such as the operation and maintenance cost structure or the reliability of the solar home system components have still not been characterized. This situation does not allow optimized maintenance structure to be designed to assure the sustainability and profitability of the operation and maintenance service. This PhD thesis aims to respond to these needs. Several studies have been carried out based on a real and large photovoltaic rural electrification programme carried out in Morocco with more than 13,000 solar home systems. An in���depth reliability assessment has been made from a 5���year maintenance database with more than 80,000 maintenance inputs. The results have allowed us to establish the real reliability functions, the failure rate and the main time to failure of the main components of the system, reporting these findings for the first time in the field of rural electrification. Both in���field experiments on the capacity degradation of batteries and power degradation of photovoltaic modules have been carried out. During the experiments both samples of batteries and modules were operating under real conditions integrated into the solar home systems of the Moroccan programme. In the case of the batteries, the results have enabled us to obtain a proposal of definition of death of batteries in rural electrification. A cost assessment of the Moroccan experience based on a 5���year accounting database has been carried out to characterize the cost structure of the programme. The results have allowed the major costs of the photovoltaic electrification to be defined. The overall cost ratio per installed system has been calculated together with the necessary fees that users would have to pay to make the operation and maintenance affordable. Finally, a mathematical optimization model has been proposed to design maintenance structures based on the previous study results. The tool has been applied to the Moroccan programme with the aim of validating the model.

Fault management techniques for systems with SRAM-based FPGAs

Las Field-Programmable Gate Arrays (FPGAs) SRAM se construyen sobre una memoria de configuraci��n de tecnolog��a RAM Est��tica (SRAM). Presentan m��ltiples caracter��sticas que las hacen muy interesantes para dise��ar sistemas empotrados complejos. En primer lugar presentan un coste no-recurrente de ingenier��a (NRE) bajo, ya que los elementos l��gicos y de enrutado est��n pre-implementados (el dise��o de usuario define su conexionado). Tambi��n, a diferencia de otras tecnolog��as de FPGA, pueden ser reconfiguradas (incluso en campo) un n��mero ilimitado de veces. Es m��s, las FPGAs SRAM de Xilinx soportan Reconfiguraci��n Parcial Din��mica (DPR), la cual permite reconfigurar la FPGA sin interrumpir la aplicaci��n. Finalmente, presentan una alta densidad de l��gica, una alta capacidad de procesamiento y un rico juego de macro-bloques. Sin embargo, un inconveniente de esta tecnolog��a es su susceptibilidad a la radiaci��n ionizante, la cual aumenta con el grado de integraci��n (geometr��as m��s peque��as, menores tensiones y mayores frecuencias). Esta es una precupaci��n de primer nivel para aplicaciones en entornos altamente radiativos y con requisitos de alta confiabilidad. Este fen��meno conlleva una degradaci��n a largo plazo y tambi��n puede inducir fallos instant��neos, los cuales pueden ser reversibles o producir da��os irreversibles. En las FPGAs SRAM, los fallos inducidos por radiaci��n pueden aparecer en en dos capas de arquitectura diferentes, que est��n f��sicamente superpuestas en el dado de silicio. La Capa de Aplicaci��n (o A-Layer) contiene el hardware definido por el usuario, y la Capa de Configuraci��n contiene la memoria de configuraci��n y la circuiter��a de soporte. Los fallos en cualquiera de estas capas pueden hacer fracasar el sistema, lo cual puede ser ��s o menos tolerable dependiendo de los requisitos de confiabilidad del sistema. En el caso general, estos fallos deben gestionados de alguna manera. Esta tesis trata sobre la gesti��n de fallos en FPGAs SRAM a nivel de sistema, en el contexto de sistemas empotrados aut��nomos y confiables operando en un entorno radiativo. La tesis se centra principalmente en aplicaciones espaciales, pero los mismos principios pueden aplicarse a aplicaciones terrenas. Las principales diferencias entre ambas son el nivel de radiaci��n y la posibilidad de mantenimiento. Las diferentes t��cnicas para la gesti��n de fallos en A-Layer y C-Layer son clasificados, y sus implicaciones en la confiabilidad del sistema son analizados. Se proponen varias arquitecturas tanto para Gestores de Fallos de una capa como de doble-capa. Para estos ��ltimos se propone una arquitectura novedosa, flexible y vers��til. Gestiona las dos capas concurrentemente de manera coordinada, y permite equilibrar el nivel de redundancia y la confiabilidad. Con el objeto de validar t��cnicas de gesti��n de fallos din��micas, se desarrollan dos diferentes soluciones. La primera es un entorno de simulaci��n para Gestores de Fallos de C-Layer, basado en SystemC como lenguaje de modelado y como simulador basado en eventos. Este entorno y su metodolog��a asociada permite explorar el espacio de dise��o del Gestor de Fallos, desacoplando su dise��o del desarrollo de la FPGA objetivo. El entorno incluye modelos tanto para la C-Layer de la FPGA como para el Gestor de Fallos, los cuales pueden interactuar a diferentes niveles de abstracci��n (a nivel de configuration frames y a nivel f��sico JTAG o SelectMAP). El entorno es configurable, escalable y vers��til, e incluye capacidades de inyecci��n de fallos. Los resultados de simulaci��n para algunos escenarios son presentados y comentados. La segunda es una plataforma de validaci��n para Gestores de Fallos de FPGAs Xilinx Virtex. La plataforma hardware aloja tres M��dulos de FPGA Xilinx Virtex-4 FX12 y dos M��dulos de Unidad de Microcontrolador (MCUs) de 32-bits de prop��sito general. Los M��dulos MCU permiten prototipar Gestores de Fallos de C-Layer y A-Layer basados en software. Cada M��dulo FPGA implementa un enlace de A-Layer Ethernet (a trav��s de un switch Ethernet) con uno de los M��dulos MCU, y un enlace de C-Layer JTAG con el otro. Adem��s, ambos M��dulos MCU intercambian comandos y datos a trav��s de un enlace interno tipo UART. Al igual que para el entorno de simulaci��n, se incluyen capacidades de inyecci��n de fallos. Los resultados de pruebas para algunos escenarios son tambi��n presentados y comentados. En resumen, esta tesis cubre el proceso completo desde la descripci��n de los fallos FPGAs SRAM inducidos por radiaci��n, pasando por la identificaci��n y clasificaci��n de t��cnicas de gesti��n de fallos, y por la propuesta de arquitecturas de Gestores de Fallos, para finalmente validarlas por simulaci��n y pruebas. El trabajo futuro est�� relacionado sobre todo con la implementaci��n de Gestores de Fallos de Sistema endurecidos para radiaci��n. ABSTRACT SRAM-based Field-Programmable Gate Arrays (FPGAs) are built on Static RAM (SRAM) technology configuration memory. They present a number of features that make them very convenient for building complex embedded systems. First of all, they benefit from low Non-Recurrent Engineering (NRE) costs, as the logic and routing elements are pre-implemented (user design defines their connection). Also, as opposed to other FPGA technologies, they can be reconfigured (even in the field) an unlimited number of times. Moreover, Xilinx SRAM-based FPGAs feature Dynamic Partial Reconfiguration (DPR), which allows to partially reconfigure the FPGA without disrupting de application. Finally, they feature a high logic density, high processing capability and a rich set of hard macros. However, one limitation of this technology is its susceptibility to ionizing radiation, which increases with technology scaling (smaller geometries, lower voltages and higher frequencies). This is a first order concern for applications in harsh radiation environments and requiring high dependability. Ionizing radiation leads to long term degradation as well as instantaneous faults, which can in turn be reversible or produce irreversible damage. In SRAM-based FPGAs, radiation-induced faults can appear at two architectural layers, which are physically overlaid on the silicon die. The Application Layer (or A-Layer) contains the user-defined hardware, and the Configuration Layer (or C-Layer) contains the (volatile) configuration memory and its support circuitry. Faults at either layers can imply a system failure, which may be more ore less tolerated depending on the dependability requirements. In the general case, such faults must be managed in some way. This thesis is about managing SRAM-based FPGA faults at system level, in the context of autonomous and dependable embedded systems operating in a radiative environment. The focus is mainly on space applications, but the same principles can be applied to ground applications. The main differences between them are the radiation level and the possibility for maintenance. The different techniques for A-Layer and C-Layer fault management are classified and their implications in system dependability are assessed. Several architectures are proposed, both for single-layer and dual-layer Fault Managers. For the latter, a novel, flexible and versatile architecture is proposed. It manages both layers concurrently in a coordinated way, and allows balancing redundancy level and dependability. For the purpose of validating dynamic fault management techniques, two different solutions are developed. The first one is a simulation framework for C-Layer Fault Managers, based on SystemC as modeling language and event-driven simulator. This framework and its associated methodology allows exploring the Fault Manager design space, decoupling its design from the target FPGA development. The framework includes models for both the FPGA C-Layer and for the Fault Manager, which can interact at different abstraction levels (at configuration frame level and at JTAG or SelectMAP physical level). The framework is configurable, scalable and versatile, and includes fault injection capabilities. Simulation results for some scenarios are presented and discussed. The second one is a validation platform for Xilinx Virtex FPGA Fault Managers. The platform hosts three Xilinx Virtex-4 FX12 FPGA Modules and two general-purpose 32-bit Microcontroller Unit (MCU) Modules. The MCU Modules allow prototyping software-based CLayer and A-Layer Fault Managers. Each FPGA Module implements one A-Layer Ethernet link (through an Ethernet switch) with one of the MCU Modules, and one C-Layer JTAG link with the other. In addition, both MCU Modules exchange commands and data over an internal UART link. Similarly to the simulation framework, fault injection capabilities are implemented. Test results for some scenarios are also presented and discussed. In summary, this thesis covers the whole process from describing the problem of radiationinduced faults in SRAM-based FPGAs, then identifying and classifying fault management techniques, then proposing Fault Manager architectures and finally validating them by simulation and test. The proposed future work is mainly related to the implementation of radiation-hardened System Fault Managers.