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Depuis l'introduction au début des années 2000 du standard ARINC 661 (définissant les interfaces graphiques dans les cockpits), les avions modernes, tels que l'A380, l'A350 ou le B787, intègrent des systèmes interactifs permettant à l'équipage d'interagir avec des applications interactives. Ces applications sont affichées sur des écrans à travers l'utilisation d'un dispositif similaire à un clavier et une souris. Pour des raisons d'exigences de sûreté de fonctionnement, l'utilisation de ces systèmes est limitée, à l'heure actuelle, à la commande et au contrôle de fonctions avioniques non critiques. Cependant, l'utilisation de ces systèmes dans les cockpits d'avions civils apporte de nombreux avantages (tels qu'une amélioration de l'évolutivité du cockpit) qui amènent les industriels à chercher comment l'étendre à la commande et le contrôle de systèmes avioniques critiques. Dans cette optique, nous proposons une approche duale et homogène de prévention et de tolérance aux fautes pour concevoir et développer des systèmes interactifs tolérants aux fautes. Celle-ci repose, dans un premier temps, sur une approche à base de modèles permettant de décrire de manière complète et non ambiguë les composants logiciels des systèmes interactifs et de prévenir les fautes logicielles de développement. Dans un second temps, elle repose sur une approche de tolérance aux fautes naturelles et certaines fautes logicielles résiduelles en opération, grâce à la mise en œuvre d'une solution architecturale fondée sur le principe des composants autotestables. Les contributions de la thèse sont illustrées sur une étude de cas de taille industrielle : une application interactive inspirée du système de commande et contrôle de l'autopilote de l'A380. / Since the introduction of the ARINC 661 standard (that defines graphical interfaces in the cockpits) in the early 2000, modern aircrafts such as the A380, the A350 or the B787 possess interactive systems. The crew interacts, through physical devices similar to keyboard and mouse, with interactive applications displayed on screens. For dependability reasons, only non-critical avionics systems are managed using such interactive systems. However, their use brings several advantages (such as a better upgradability), leading aircraft manufacturers to generalize the use of such interactive systems to the management of critical avionics functions. To reach this goal, we propose a dual and homogeneous fault prevention and fault tolerance approach. Firstly, we propose a model-based approach to describe in a complete and unambiguous way interactive software components to prevent as much as possible development software faults. Secondly, we propose a fault tolerant approach to deal with operational natural faults and some residual software faults. This is achieved through the implementation of a fault tolerant architecture based on the principle of self-checking components. Our approach is illustrated on a real size case study: an interactive application based on the command and control system of the A380 autopilot.

Examensarbetet genomfördes tillsammans med företaget Rol Ergo. Syftet med studien var att analysera Zigbee 3.0 och Bluetooth Low Energy 5.2 och deras lämplighet i tidskritiska system genom att studera latensen och förhållandet mellan signalstyrkan och avståndet mellan de två kommunikationsprodukter. Datainsamlingen genomfördes med en experimentell studie och utifrån kunskap som framskaffats har ett visst antal bestämda experiment utförts för att svara på frågeställningarna som ställs.  Datainsamlingen visar att både maxlatensen och typiska latensen hos Zigbee är lägre än maxlatens och typiska latens för Bluetooth Low Energy. Datainsamlingen för signalstyrkan visar att Bluetooth Low Energys signalstyrka blir mer påverkad av avståndet mellan kommunikationsprodukterna än vad Zigbees blir. Det visar även att den optimala förhållande mellan signalstyrkan och avståndet hos Zigbee är bättre än hos Bluetooth Low Energy.  Slutsatsen av arbetet är att Zigbee är mer lämpad för tidkritiska system än Bluetooth Low Energy då låg latensen prioriteras. Zigbee är även mer lämpad då lång distansen prioriteras men då bör signalstyrkan ligga runt -50dBm. Bluetooth Low Energy är dock mer lämpad då lång distans inte prioriteras och signalstyrkan inte behöver vara utmärkt för att kunna kommunicera.  Begränsningarna för arbetet är att Bluetooth Low Energy och Zigbee endast har prövats på utvecklingskortet nRF5340 DK.  På grund av den begränsade tiden så har endast ett antal bestämda experiment som har föreslagits av rådgivare på Rol Ergo utförts. / The thesis has been conducted together with  Rol Ergo company. The purpose of this study is to analyse Zigbee 3.0 and Bluetooth Low Energy 5.2 and their suitability for time-critical systems, by studying latency and the relations between signal strength and distance between two communication products. The data collection was completed by an experimental study. By using knowledge that has been collected for the study, sets of experiments will be performed to answer the research questions.  Results of the collected data indicate that both the maximum latency and the typical latency for Zigbee is significantly lower than for Bluetooth Low Energy. The collected data for signal strength shows that the signal strength for Bluetooth Low Energy is more affected by distance between the communication product, than Zigbee’s is. It also shows that the optimal ratio between signal strength and distance for Zigbee is better than for Bluetooth Low Energy. The conclusion of the study shows Zigbee to be a more suitable for time-critical systems compared to Bluetooth Low Energy when low latency is being prioritized. Zigbee is also more suitable for time-critical systems when long distance is being prioritized, however the signal strength must then be around -50 dBm. Bluetooth Low Energy is more suitable when long distance is not the priority, and the signal strength does not have to be excellent to be able to communicate.  The limitations for this thesis are that Bluetooth Low Energy and Zigbee will only be tested on the nRF5349 Development Kit. given limited time, only a certain of experiments, whereas some have been suggested by advisors from Rol Ergo, has been carried out.

AirSim is a new simulator developed as a plugin for the Unreal Engine, aiming to be a useful tool aiding the development and testing of algorithms for autonomous vehicles. Due to AirSim still being in its infancy there is little to none research available of its possibilities or detailed guidelines and tutorials on how to use its APIs.Rust is a new systems programming language with the purpose of being safe, practical and concurrent which through design choices can solve some of the major drawbacks of the C programming language such as memory leaks, thread management, and segmentation faults.Researching the features of AirSim and its different ways of communicating, we determine the possibility of implementing a custom flight controller in Rust and C able to control a drone in the simulator and evaluate the capabilities of Rust compared to C. This is conducted by reading available documentation for AirSim, studying the source code and learning about the communication protocols used by AirSim.This thesis results in an implementation of a custom flight controller in Rust and C that controls a drone in AirSim using a communication protocol named MAVLink which enables fine-grained control of the motors. The conclusion made about the comparison of Rust and C is that both languages were able to implement the safety-critical functionality of the flight controller and that Rust provided capabilities which could be useful when developing safety-critical systems. / AirSim är en ny simulator utvecklad som ett plugin för Unreal Engine, med målet att fungera som ett hjälpmedel inom utveckling och testning av algoritmer för autonoma fordon. På grund av att AirSim fortfarande är väldigt ungt finns väldigt lite forskning tillgänglig om dess möjligheter eller detaljerade riktlinjer och beskrivningar för användningen av dess APIer.Rust är ett nytt programmeringsspråk med målet att vara säkert, praktiskt och parallellt vilket genom designval kan lösa några av de största problemen med programmeringsspråket C som till exempel minnessläckor, trådhantering och segmenteringsfel.Genom att undersöka funktionerna i AirSim och dess olika sätt att kommunicera, utforskar vi möjligheten av att utveckla en egen flygkontroller i Rust och C som kan styra en drönare i simulatorn och utvärdera Rust i förhållande till C. Detta genomförs genom att läsa tillgänglig dokumentation för AirSim, studera källkoden och lära oss de kommunikationsprotokoll som används av AirSim.Denna avhandling resulterar i implementationen av en egen flygkontroller i Rust och C som styr en drönare i AirSim med kommunikationsprotokollet MAVLink, vilket möjliggör en noggrann kontroll av motorerna. Slutsatsen gällande Rust och C är att båda språken fungerade väl för implementationen av säkerhetsritiska funktioner i flygkontrollern samt att Rust erbjöd förmågor som kan visa sig vara användbara vid utveckling av säkerhetskritiska system.

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The evidence from the literature suggests that Information Technology adoption (IT) governance in organisations is still a challenge. The diversity of application and the ever-increasing use of IT results in making decisions on IT adoption a major challenge for organisations. The decision about using a particular technology from an organisational perspective is problematic since individual users have different worldviews. The implicit assumption in IT adoption literature is that stakeholders always reach consensus during IT adoption decision making in organisations. This study explored the existing models and frameworks in order to develop a preliminary improved IT adoption governance framework. This study used a case study sequential explanatory mixed methods research approach to validate the preliminary IT adoption governance framework. The first validation phase of the framework was done using a quantitative approach followed by the second validation phase based on qualitative interviews. The last validation was done after integrating the quantitative and qualitative results to produce the refined framework. The results suggest that the developed framework may improve IT adoption governance in organisations. The results showed that the framework components facilitate IT adoption governance in organisations. The results also suggest that the components have an association with each other except for the Technology Acceptance Model component. The results indicate that stakeholder participation and hard systems thinking components have a strong predictive impact on IT governance framework component perception in organisations. The study results suggest that IT adoption decision makers need to balance different stakeholders’ demands during IT adoption decision making in organisations. The framework helps in that regard by reconciling different stakeholders’ demands through collective IT adoption decision making. The strength of the framework is its integration of theories from various disciplines in understanding stakeholder expectations. On that basis the framework is in a better position to offer more insight into understanding challenges of IT adoption decision making than existing frameworks and models. The framework offers a potentially valuable basis for future research in IT adoption decision making in organisations. The results suggest that the framework may facilitate IT adoption in organisations using different components. / Information Science / D. Litt. et Phil. (Information systems)

Made available in DSpace on 2016-04-04T18:31:33Z (GMT). No. of bitstreams: 1 Mauricio Becker.pdf: 1680814 bytes, checksum: e32eecc9e8f4e602513a2049aa488491 (MD5) Previous issue date: 2012-12-03 / In the current globalized and connected context where companies and organizations increasingly rely on their information technology infrastructure for business continuity, such critical systems and applications need to be available and operational for end users and customers almost twenty-four hours per day over the three hundred sixty-five days of the year. In view of this, this research sought to identify the state of the art in terms of technologies for high availability computing environments and how best practice guides for IT Governance & Management can help to maintain available and operational the business critical systems. As a complement, it sought through the application of a survey research to understand the existing IT practices in one of three states with greatest economic importance in the Brazilian Northeast area. The study was conducted among December 2011 and March 2012 and aimed to evaluate current investments in IT resources, identify the main causes of unplanned downtimes and measure their impacts. From the data analysis it was possible to identify improvement opportunities regarding infrastructure, people, processes and services in order to minimize the unavailability of business critical systems for companies and organizations. / No atual contexto globalizado e conectado, as empresas e organiza??es dependem cada vez mais de suas infraestruturas de tecnologia da informa??o para a continuidade de seus neg?cios. Por esse motivo, tais sistemas e aplica??es cr?ticos ?s organiza??es necessitam estar dispon?veis e operacionais aos usu?rios internos e clientes por praticamente vinte e quatro horas por dia ao longo dos trezentos e sessenta e cinco dias do ano. Diante disto, esta pesquisa buscou apreender o estado da arte em termos de tecnologias para ambientes computacionais de alta disponibilidade e como guias de melhores pr?ticas de Governan?a e Gerenciamento de TI podem contribuir para manterdispon?veis e operacionais os sistemas cr?ticos ao neg?cio. Como complemento, buscou por meio da aplica??o de um survey compreender a pr?tica de TI existente em um dos tr?s Estados do nordeste brasileiro de maior relev?ncia econ?mica. O estudo foi realizado entre dezembro de 2011 e mar?o de 2012 e teve por objetivos avaliar os atuais investimentos em recursos de TI, mensurar os impactos e identificar as principais causas das paradas n?o programadas. Da an?lise dos dados, foi poss?vel apontar as oportunidades de melhoria no que tange infraestrutura, pessoas, processos e servi?os visando minimizar a indisponibilidade dos sistemas cr?ticos ao neg?cio de empresas e organiza??es.

Reliability of low-level operating-system (OS) code is an indispensable requirement. This includes functional properties from the safety-liveness spectrum, but also quantitative properties stating, e.g., that the average waiting time on locks is sufficiently small or that the energy requirement of a certain system call is below a given threshold with a high probability. This paper reports on our experiences made in a running project where the goal is to apply probabilistic model checking techniques and to align the results of the model checker with measurements to predict quantitative properties of low-level OS code.

Made available in DSpace on 2014-12-17T15:48:03Z (GMT). No. of bitstreams: 1 HanielMB_DISSERT.pdf: 4925062 bytes, checksum: b4c15cc32318b96fa9ccd3be61b6e7e6 (MD5) Previous issue date: 2012-11-01 / PLCs (acronym for Programmable Logic Controllers) perform control operations, receiving information from the environment, processing it and modifying this same environment according to the results produced. They are commonly used in industry in several applications, from mass transport to petroleum industry. As the complexity of these applications increase, and as various are safety critical, a necessity for ensuring that they are reliable arouses. Testing and simulation are the de-facto methods used in the industry to do so, but they can leave flaws undiscovered. Formal methods can provide more confidence in an application s safety, once they permit their mathematical verification. We make use of the B Method, which has been successfully applied in the formal verification of industrial systems, is supported by several tools and can handle decomposition, refinement, and verification of correctness according to the specification. The method we developed and present in this work automatically generates B models from PLC programs and verify them in terms of safety constraints, manually derived from the system requirements. The scope of our method is the PLC programming languages presented in the IEC 61131-3 standard, although we are also able to verify programs not fully compliant with the standard. Our approach aims to ease the integration of formal methods in the industry through the abbreviation of the effort to perform formal verification in PLCs / Controladores L?gico Program?veis (PLCs Programmable Logic Controllers, em ingl?s) desempenham fun??es de controle, recebendo informa??es do ambiente, processando-as e modificando este ambiente de acordo com os resultados obtidos. S?o comumente utilizados na ind?stria nas mais diversas aplica??es, do transporte de massa ? ind?stria do petr?leo, g?s e energias renov?veis. Com o crescente aumento da complexidade dessas aplica??es e do seu uso em sistemas cr?ticos, faz-se necess?ria uma forma de verifica??o que propicie mais confian?a do que testes e simula??o, padr?es mais utilizados na ind?stria, mas que podem deixar falhas n?o tratadas. M?todos formais podem prover maior seguran?a a este tipo de sistema, uma vez que permitem a sua verifica??o matem?tica. Neste trabalho fazemos uso do M?todo B, que ? usado com sucesso na ind?stria para a verifica??o de sistemas cr?ticos, possui amplo apoio ferramental e suporte ? decomposi??o, refinamento e verifica??o de corretude em rela??o ? especifica??o atrav?s de obriga??es de prova. O m?todo desenvolvido e apresentado aqui consiste em gerar automaticamente modelos B a partir de programas para PLCs e verific?-los formalmente em rela??o a propriedades de seguran?a, estas derivadas manualmente a partir dos requisitos do sistema. O escopo do trabalho s?o as linguagens de programa??o para PLCs do padr?o IEC 61131-3, mas sistemas com linguagens que apresentem modifica??es em rela??o ao padr?o tamb?m s?o suportados. Esta abordagem visa facilitar a integra??o de m?todos formais na ind?stria atrav?s da diminui??o do esfor?o para realizar a verifica??o formal de PLCs

The evidence from the literature suggests that Information Technology adoption (IT) governance in organisations is still a challenge. The diversity of application and the ever-increasing use of IT results in making decisions on IT adoption a major challenge for organisations. The decision about using a particular technology from an organisational perspective is problematic since individual users have different worldviews. The implicit assumption in IT adoption literature is that stakeholders always reach consensus during IT adoption decision making in organisations. This study explored the existing models and frameworks in order to develop a preliminary improved IT adoption governance framework. This study used a case study sequential explanatory mixed methods research approach to validate the preliminary IT adoption governance framework. The first validation phase of the framework was done using a quantitative approach followed by the second validation phase based on qualitative interviews. The last validation was done after integrating the quantitative and qualitative results to produce the refined framework. The results suggest that the developed framework may improve IT adoption governance in organisations. The results showed that the framework components facilitate IT adoption governance in organisations. The results also suggest that the components have an association with each other except for the Technology Acceptance Model component. The results indicate that stakeholder participation and hard systems thinking components have a strong predictive impact on IT governance framework component perception in organisations. The study results suggest that IT adoption decision makers need to balance different stakeholders’ demands during IT adoption decision making in organisations. The framework helps in that regard by reconciling different stakeholders’ demands through collective IT adoption decision making. The strength of the framework is its integration of theories from various disciplines in understanding stakeholder expectations. On that basis the framework is in a better position to offer more insight into understanding challenges of IT adoption decision making than existing frameworks and models. The framework offers a potentially valuable basis for future research in IT adoption decision making in organisations. The results suggest that the framework may facilitate IT adoption in organisations using different components. / Information Science / D. Litt. et Phil. (Information systems)