Applying Hypervisor-Based Fault Tolerance Techniques to Safety-Critical Embedded Systems

This document details the work conducted through the development of this thesis, and it is structured as follows: • Chapter 1, Introduction, has briefly presented the motivation, objectives, and contributions of this thesis. • Chapter 2, Fundamentals, exposes a series of concepts that are necessary to correctly understand the information presented in the rest of the thesis, such as the concepts of virtualization, hypervisors, or software-based fault tolerance. In addition, this chapter includes an exhaustive review and comparison between the different hypervisors used in scientific studies dealing with safety-critical systems, and a brief review of some works that try to improve fault tolerance in the hypervisor itself, an area of research that is outside the scope of this work, but that complements the mechanism presented and could be established as a line of future work. • Chapter 3, Problem Statement and Related Work, explains the main reasons why the concept of Hypervisor-Based Fault Tolerance was born and reviews the main articles and research papers on the subject. This review includes both papers related to safety-critical embedded systems (such as the research carried out in this thesis) and papers related to cloud servers and cluster computing that, although not directly applicable to embedded systems, may raise useful concepts that make our solution more complete or allow us to establish future lines of work. • Chapter 4, Proposed Solution, begins with a brief comparison of the work presented in Chapter 3 to establish the requirements that our solution must meet in order to be as complete and innovative as possible. It then sets out the architecture of the proposed solution and explains in detail the two main elements of the solution: the Voter and the Health Monitoring partition. • Chapter 5, Prototype, explains in detail the prototyping of the proposed solution, including the choice of the hypervisor, the processing board, and the critical functionality to be redundant. With respect to the voter, it includes prototypes for both the software version (the voter is implemented in a virtual machine) and the hardware version (the voter is implemented as IP cores on the FPGA). • Chapter 6, Evaluation, includes the evaluation of the prototype developed in Chapter 5. As a preliminary step and given that there is no evidence in this regard, an exercise is carried out to measure the overhead involved in using the XtratuM hypervisor versus not using it. Subsequently, qualitative tests are carried out to check that Health Monitoring is working as expected and a fault injection campaign is carried out to check the error detection and correction rate of our solution. Finally, a comparison is made between the performance of the hardware and software versions of Voter. • Chapter 7, Conclusions and Future Work, is dedicated to collect the conclusions obtained and the contributions made during the research (in the form of articles in journals, conferences and contributions to projects and proposals in the industry). In addition, it establishes some lines of future work that could complete and extend the research carried out during this doctoral thesis.Programa de Doctorado en Ciencia y Tecnología Informática por la Universidad Carlos III de MadridPresidente: Katzalin Olcoz Herrero.- Secretario: Félix García Carballeira.- Vocal: Santiago Rodríguez de la Fuent

Procesado en tiempo real de rutas e incidencias aéreas para la gestión de drones comerciales

Currently, we all know the concept of Unmanned Aerial Vehicles (UAV), although we refer to them colloquially as drones. See one of these small aircraft, which need no pilot on board, spraying a plantation, recording the traffic situation, flying over the scene of a concert or delivering a package are situations that, although recently seemed science fiction, start to assumme a strong note of reality. The advancement of technology allows these devices, historically linked to military operations, reach millions of homes and businesses around the world, helping people to perform tasks that were not possible before, or had a very high risk to be. As it has happened with other technologies at this times that we live in, what began as an eccentricity has become an advantageous option and, soon, will be an irreplaceable necessity. Drones begin to be everywhere and, of course, begin to create problems. Among its infinite virtues are some capabilities that, for misconduct or sheer recklessness, can cause serious problems in airspace or threaten physical integrity and privacy of people. Are we prepared to meet these challenges? Will we be prepared when drones that fly through the skies every day will be counted by millions? In this project these questions are addressed, posing the problem and trying to design a valid solution utilizing new Big Data analysis tools. In addition, a prototype showing a first implementation of this design it is presented and tested.Actualmente, todos conocemos el concepto de los vehículos aéreos no tripulados, aunque nos refiramos a ellos coloquialmente como drones. Ver a una de estas pequeñas aeronaves, que no necesitan de piloto a bordo, fumigando una plantación, grabando la situación del tráfico, sobrevolando el escenario de un concierto o repartiendo un paquete son situaciones que, aunque hace poco parecían de ciencia ficción, comienzan a coger claros tintes de realidad. El avance de la tecnología permite que estos aparatos, históricamente ligados a operaciones militares, lleguen a millones de hogares y empresas de todo el mundo, ayudando al ser humano a realizar tareas que antes no eran posibles, o tenían un riesgo muy elevado. Como ha ocurrido con otras tecnologías en este tiempo que nos ha tocado vivir, lo que comenzó siendo una excentricidad se ha convertido en una opción ventajosa y, dentro de poco, será una necesidad irremplazable. Los drones comienzan a estar en todas partes y, evidentemente, comienzan a crear problemas. Entre sus infinitas virtudes se encuentran algunas capacidades que, por mala intención o por pura imprudencia, pueden provocar graves accidentes en el espacio aéreo o atentar contra la integridad física y la privacidad de las personas. ¿Estamos preparados para hacer frente a estos desafíos? ¿Lo estaremos cuando se cuenten por millones los drones que surquen los cielos cada día? En este proyecto se abordan estas preguntas, planteando el problema y tratando de diseñar una solución válida que utilice las tecnologías de análisis de Big Data existentes hoy en día. Además, se presenta y se pone a prueba un prototipo que muestra una primera implementación de este diseño.Ingeniería en Tecnologías de Telecomunicació

Coronary artery aneurysms, insights from the international coronary artery aneurysm registry (CAAR).

Coronary Aneurysms are a focal dilatation of an artery segment >1.5-fold the normal size of adjacent segments. Although some series have suggested a prevalence of 0.3-12%, data are lacking. In addition, they are not mentioned in practice guidelines. Our aim was investigate its prevalence, management and long-term outcomes. The coronary artery aneurysm registry (CAAR) involved 32 hospitals across 9 countries in America and Europe. We reviewed 436,467 consecutive angiograms performed over the period 2004-2016. Finally, 1565 patients were recruited. Aneurysm global prevalence was 0.35%. Most patients were male (78.5%) with a mean age of 65 years and frequent cardiovascular risk factors. The main indication for angiogram was an acute coronary syndrome, 966 cases. The number of aneurisms was ≤2 per patient in 95.8% of the cases, mostly saccular, most frequently found in the left anterior descending and with numbers proportional with coronary stenosis. Aortopathies were related with more aneurysms too. Most patients received any revascularization procedure (69%), commonly percutaneous (53%). After a median follow-up of 37.2 months, 485 suffered a combined event (MACE) and 240 died. Without major differences comparing CABG vs PCI, MACE and death were more frequent in patients who received bare metal stents. Coronary artery aneurysms are not uncommon. Usually, they are associated with coronary stenosis and high cardiovascular risk. Antiplatelet therapy seems reasonable and a percutaneous approach is safe and effective